A rainy day in Santa Barbara, and Jeff Bridges sits in his garage, wondering where his favourite spectacles have got to. We are in the middle of a rangy conversation on a video call, meandering our way from Bob Dylan to the anthropomorphism of bees, via Crazy Heart, Cutter’s Way and The Big Lebowski. There are sidetracks and double-backs and loose threads. Intermittently, an unseen assistant hands the actor pairs of glasses seemingly identical to the ones he is already wearing. Bridges, in a soft brown cardigan, inspects each pair and dismisses them. “Where was I?” he asks.

The garage here serves as Bridges’ jam space and ceramics workshop. He has drums set up for his grandson, and a picture of Captain Beefheart on the wall. Since December, when his FX series The Old Man was cancelled, the 75-year-old has been spending more of his days here. “Now I’ve got some time for letting some other things bubble up and I’m really happy about that,” he says. “A lot of music, some more art stuff.”

Bridges is good at finding the silver lining. Mention the recent loss of his Malibu home in the Los Angeles fires, for instance, and he is sanguine. “We’ve lost five homes to fires, earthquakes, floods. We’re waiting for the locusts,” he says. His 2020 diagnosis and subsequent treatment for non-Hodgkin lymphoma – or, in Bridges words, “some real health issues” – is mentioned only in passing, as the catalyst for him to release more music: “Hey,” he reasons, “if you’ve got some stuff that you want to share, now’s the time, man!” I tell him how despite it all he seems remarkably chipper, and he smiles. “Absolutely,” he says. “I’m happy.”

The primary focus of our conversation today is intended to be Slow Magic, a collection of Bridges songs lost for close to 50 years and now due to be released on Record Store Day. The way the release came about, he says, “is so mysterious and wonderful to me. Shall I give you a little history?” He launches into a story that involves the musicians Keefus Ciancia and T Bone Burnett, a Squarespace advertisement for the Super Bowl, the 1975 comedy Hearts of the West, the New Age music charts, and a single cassette tape of some tunes Bridges had set down with some old high school buddies, labelled “July 1978”. One soon grasps that much of Bridges’ life has moved this way, in bursts of what we might regard as cosmic serendipity and connection.

Bridges was born into a well-known Hollywood family. His mother, Dorothy, and his father, Lloyd, were both actors, as was his older brother, Beau. Although the young Jeff showed promise in art and music, his father encouraged him to join the family business, taking him along to set, securing him minor roles on his productions. “I had questions about what I was going to do, and my dad would say: ‘Jeff, don’t be ridiculous, that’s the wonderful thing about acting, it’s going to call upon all of your interests.’”

All the family loved music. They would sit around the piano, singing show tunes together. One of Bridges’ earliest memories involves the Broadway composer Meredith Willson visiting the family home to try to persuade his father to take the lead role in The Music Man. “His wife, Rini, was playing the piano and Meredith Willson was coming up to me singing: ‘You got trouble! Right here in River City!’”

He was a teenager in the 1960s, just as music shifted gear from the early rock’n’roll of Chuck Berry and the Everly Brothers to the likes of the Beatles, Bob Dylan and the Rolling Stones. “I mean every day, can you imagine, waking up going to school and here are the new Beatles songs?” he says. “And that happened over and over! You take it for granted, kind of, but it’s amazing!”

Bridges’ high school was largely made up of the children of the entertainment industry. He hung out with an artsy bohemian crowd, rather than the jocks, each school day starting by getting stoned in his Buick while he and his buddies listened to the radio: “[There was] a lot of drug experimentation you know, during those times.”

On Wednesday evenings, a group of them would meet for a jam session at his friend Steve Baim’s home. “There was a main rule that there were no songs allowed,” Bridges says. “Singing was encouraged, and making up songs, but nothing that would be played on the radio or anything like that. Just a big jam session.” As they left high school and moved through their lives, the Wednesday Night Jams continued – a way of rooting the group in their city, their friendship and their creativity. At some point around 1977, Bridges, who had been writing music alongside acting, invited his friends over to record some of his tunes. “And the album is a result of that.”

Despite his father’s advice, music had always remained an alluring and viable career path for Bridges. In the late 60s he even sold two songs to Quincy Jones, who used one of them, Lost in Space, for the soundtrack of John and Mary, starring Dustin Hoffman and Mia Farrow. As time went on, the indecision continued. “I’d done 10 movies, I’d been nominated for an Academy Award [best supporting actor for The Last Picture Show, 1971], and I still wasn’t…” He pauses, and his eyes glance off to the assistant once more. “Oh thank you dear, I appreciate that,” he says, taking the latest pair of spectacles. “Those are the ones!” He says, then looks at them more closely. “No, these are not the ones!”

Something of a shift happened after making 1973 motor sports movie The Last American Hero. “I had a great time making it, but usually after a movie your pretend muscle gets exhausted,” Bridges says. “You don’t want to pretend any more, you just want to be who you really are and not be in character.”

Shortly after filming wrapped, his agent was approached by the director John Frankenheimer with a part in his adaptation of Eugene O’Neill’s The Iceman Cometh. Bridges knew it would be a big deal – Frederic March, Robert Ryan and Lee Marvin were already signed up. Nevertheless, he was unsure. He told his agent to turn down the role. Five minutes later, he received a call from Lamont Johnson, director of The Last American Hero. “He said: ‘I heard you turned down The Iceman Cometh?’ I said ‘Yeah Monty, I’m bushed, man.’ And he says, ‘You’re bushed? You’re an ass!’ And he hung up on me!”

Bridges took stock and decided “to do a little experiment on myself and go kind of against what my intuition is telling me”. He took the role, loved the movie, and decided he would throw his hat fully into the acting ring.

It was an early example of Bridges exploring what he regards as the resistant element in himself. “I find I have a lot of resistance, that’s kind of how I roll,” he says. “To do a movie, to bring me to the party, I resist, I resist. And there’s such satisfaction in exploring that resistance and getting on the other side, not being afraid of it.”

Lately, he has been examining his resistance to cold. “I’m getting into the cold-plunging, I’ve been doing that for a while, and my relationship with cold has shifted a bit,” he says. “Normally you think of cold as an enemy, but it’s just a feeling. All of those different emotions that come up, they’re no big thing man! Come on!” He was always this way, he says, always resistant. “I don’t think I’ve changed much since I was a little kid. I feel basically the same.” I ask Bridges how he would describe himself at his essence, and he leans back in his chair and thinks. After a moment, he smiles, broadly. “Frightened, and game.”

He is reluctant to be drawn on how different his relationship with music might be to his relationship with acting – whether it still holds any of that same resistance, if it requires him to use his “pretend” muscle. “It’s a facet of myself,” he says. “I don’t think we ultimately know who we really are all the time. The task for all these different things, whether it’s acting, music, painting, ceramics, the main task is getting out of the way, letting the thing come through you. And it can be frightening sometimes. But sometimes it just has its way with you, and when that happens, man it’s a gas! And when it happens with a bunch of other artists and you’re all doing it together, it’s real magic. It’s the magic of trees and flowers.”

Music has often been the thing that has glued together the various facets of himself, and connected Bridges to others. “Whether it’s making a movie or music, you’re harmonising,” he says. “You’re saying: let’s combine our strengths here and see what we can come up with and make it beautiful and real.”

Often, he will make a playlist for the character he’s playing (for the Dude in The Big Lebowski, it was “a lot of Creedence”). “Then you play them in the makeup trailer,” he says. “You get made up with all the guys in the show, you make that transition from who you are back into your characters. You get painted, you share music.”

He recalls shooting 1984’s Against All Odds in Mexico with Taylor Hackford, and how on their first night in Mexico “we split a bottle of tequila, and went through the whole Beatles catalogue”. How, stuck for nine months on the set of Heaven’s Gate in Montana, Kris Kristofferson and T Bone Burnett invited a string of musical friends to join them. “And we would just jam all the time. When we weren’t working, we were playing.” Later, when he was offered the lead in Crazy Heart, playing an alcoholic country singer trying to turn his life around, he took the part because Burnett signed on to write the score.

In 2003, Bridges appeared alongside Bob Dylan in Masked and Anonymous. One day the director, Larry Charles, made a suggestion: “Why don’t you and Bob go off and you teach Bob some acting? Go and do some improvisation or something.” Bridges, resistant, eventually agreed. “He was so great to work with,” he says. “He’s such an incredible actor. I mean his presence, right?”

Not long afterwards, Bridges was in his trailer, playing guitar, when Dylan appeared in the doorway. “He said ‘Hey man, you want to jam?’” Bridges still looks flabbergasted. I ask if he saw A Complete Unknown. “Yeah, yeah,” he says. “They all did such a great job but …” He seems puzzled by the film’s existence. “You know, you got the real thing …”

Lately, Bridges has been spending a little time going through what he calls his “song mine”, wondering what to do with all the tunes he’s written. He is still writing. The songs fill his notebooks and his GarageBand files. Sometimes he sets them down with Ciancia in their band the Abiders. Sometimes he puts them out as rough sketches on his website under the banner Emergent Behaviour. He asks only that if you dig them, you might make a donation to his chosen charities, No Kid Hungry and the Amazon Conservation Team. “Let’s create beautifully together,” the website suggests.

“I wrote a song recently about my old buddy John Goodwin,” Bridges tells me. He and Goodwin grew up in the same neighbourhood, and Goodwin became a professional songwriter – he provided material for the Crazy Heart soundtrack, which won an Oscar and two Grammys, and for Bridges’ self-titled 2011 album, recorded after the film’s success.

Bridges has called his Goodwin tribute song We Know That One. “I don’t know what style you’d call it. It’s my own style, kind of. Let me see if I can find it …” He picks up a tablet, peers at the screen. “All right. Let’s see here. Scrolling, scrolling, music, lyrics, my lyrics, my chorus, lyrics …”

In the quiet of his garage, Bridges leans far back in his chair, hands behind his head, and begins to sing. His voice is dusky, and warm and kind, and as he sings, something about him seems to glow. The music is having its way with him, and it is real magic; the magic of trees and flowers.

“From the top it looks deep, from the bottom it looks high,
Dive into the lake through the reflection of the sky.
No need feeling lonely Johnny, on this road heading home,
We’re all heading that way, no one’s really alone.
Can’t you hear us laughing as we cover our gold with the ashes,
Our freedom, yeah we’re ditching our souls.
Johnny can’t you see we use hilarity to numb.
I think we’re just too damn sensitive Johnny, we couldn’t be that dumb.
Do we need some kind of friction? Do we need some kind of brakes?
Something dragging in the dirt, is that what it takes to get us home Johnny, get us home safe?
In that case, maybe laughing ain’t too bad while we wait.
I can feel my soul waiting for me up ahead, tapping his foot, he’s covered all bets.
He’s waiting with yours Johnny, they’re playing in the sun,
Hear that tune they’re playing, we know that one …”

• Slow Magic, 1977-78 will be released on Light in the Attic on 12 April