DETROIT, July 20 — There were more arcade games than people inside Eminem’s studio on a recent summer afternoon, and the crunch of NFL highlights — not music — filled the silence. At work in the unmarked, grey suburban building, the rapper born Marshall Mathers held a pen and a tattered Detroit Lions composition book, writing in solitude for no project in particular.

“I have a thinking job,” he said, settling onto a black leather couch and turning down the TV. “I write a lot of things down, and sometimes I never use them. It’s just the exercise.”

At 42, with tens of millions of albums sold, 15 Grammys (including two won in 2015) and an Academy Award for best original song (“Lose Yourself” in 2002), Eminem knows he can pick his spots. In the era of Drake and Kanye West, he exists on a separate plane of rap celebrity — rarely photographed, without a personal online presence — removed in sound and style from hip-hop’s current sphere of influence.

Yet when he pops up, people listen: “The Marshall Mathers LP 2,” his dense 2013 album, has sold more than 2 million copies in the United States. Rather than rush a follow-up, he has re-emerged this summer as the executive producer and lead artist on the soundtrack for “Southpaw,” out July 24, the redemption story of a beaten-down boxer played by Jake Gyllenhaal.

The role of the fighter, as conceived five years ago by screenwriter Kurt Sutter (“Sons of Anarchy”) and director Antoine Fuqua (“Training Day”), was originally meant for Eminem, who has only cameoed as himself in comedies since starring in the semiautobiographical “8 Mile” more than a decade ago. But when it came time to commit to the film, he chose to finish and promote his album instead.

Still hoping to be involved with “Southpaw,” Eminem corralled some longtime friends and collaborators — 50 Cent, Slaughterhouse, Busta Rhymes — for an assault of guitar-heavy, underdog pump-up songs, including “Phenomenal,” his own montage-driving single. (In support of the project, which will be released on Shady Records the same day as the film, he has also been featured as a guest on Apple’s new Beats 1 radio and showed up to sing Bob Seger songs with Stephen Colbert on a Michigan public access station.)

Conveniently, the “Southpaw” comeback narrative allowed Eminem to address some of his own anxieties about life as an aging rapper with an uneven latter career — “You’re moving onto the next, but is the respect gone?” he raps on “Kings Never Die.”

In conversation, Eminem was focused to the point of seeming solemn but also uncertain about his future, oscillating between intense eye contact and staring at the floor. He insisted not much had changed since his days as a hip-hop insurgent, including his sense of humour and competitive spirit. But he acknowledged that stasis, too, could be dangerous. These are excerpts from the conversation.

How did you approach putting together a soundtrack for a film that wasn’t your own?

We wanted to make sure that the songs would remind you of the movie years down the road. When you think of “Don’t You (Forget About Me),” you think of “The Breakfast Club.” When you think of “Eye of the Tiger,” you think of “Rocky.”

Or “Lose Yourself” — did you feel pressure to live up to “8 Mile”?

With this particular movie, I’m not in it, so I couldn’t be (the character) Billy Hope in the song. I tried to make something that was thematic — self-empowering, about being in a corner and fighting back.

The energy of the film is pretty masculine, and the soundtrack is almost all male. How did Gwen Stefani get in the mix on “Kings Never Die”? You’ve poked some fun at her in music before.

I don’t think it was ever anything that was disrespectful. I mean, maybe I said she could pee-pee on me, but I don’t care who you are — that’s funny regardless. But I’ve always respected Gwen Stefani. She’s an incredible talent, but also her longevity is one of the reasons she was perfect for that song.

What’s your relationship like with 50 Cent these days? He’s on the soundtrack and in the movie.

Same as it’s always been, pretty much. I love Fif’, man.

Making albums has taken a back seat for him, and he’s become this celebrity personality and businessman. Dr Dre is doing something similar. Do you ever think about moving into different worlds like them?

With 50, I could always see that coming, even from the start. He was always so business-minded. He’s always been so in tune with what the next move is, where I may be — I hate to say it — but I tend to be more narrow-minded. Just so tunnel vision with the music.

Are you plugged in with current rap music?

I try to stay up on everything that’s out. I love (Lil) Wayne, Drake, Big Sean, Schoolboy Q. I love Kendrick (Lamar). I just try to pay attention to what’s out. Wayne puts out a new song, and my ears perk up. There are certain artists that make me do that just because of the caliber that they rhyme at — it’s like candy to me. Kendrick, the way he puts albums together — front to back, they’re like pieces of art. But hip-hop needs Drake, too. Hip-hop needs Big Sean. I feel like hip-hop is in a good place right now. There’s this balance of things going on, and it feels like some of the best rappers are the most successful. Sometimes that’s not the case.

Do you think Twitter and Instagram have affected rap?

I know there are a lot of Twitter beefs. People used to just make songs. But it is what it is. The world’s forever changing, and you’ve just gotta adapt and evolve.

You’re not one of those “it was better in my day” types?

For sure, I don’t want to be that guy. You take the good with the bad. It’s one of the things I really respect about Jay (Z). In my opinion, he’s never had a lull in his career. It’s always just been so consistent; he’s so in tune with what is current and what’s cool to do.

Do you feel like you’ve had a lull in your career?

Oh, me? For sure. Probably the “Encore” days. Personally, I look at “Relapse” as a lull. The rest is subject to opinion.

What is your day-to-day life like in between albums?

A lot of work. I’m usually in the studio five to six days a week, trying to think of my next move. Every now and then, I’ll reassess where I’m at in my career. I’m usually trying to think of what I’m going to do next.

Are you working on a solo album?

Not as of yet. But I’m just trying to figure out what to do next musically. There’ll be a certain page that I get on, and I’m like, “OK, I’ve done it this way.” Sometimes I think that if I get comfortable or set in my ways of doing something, maybe I should step back for a minute and figure out how to mix it up a little bit.

Do you feel like you’re still topping yourself?

I feel like I’m still trying to. And sometimes I don’t know if that’s always a good thing. I don’t want to make it so that by the time I’m done with a song, you didn’t even understand what just happened. That’s what I try not to do. I’m my own worst nightmare in that sense.

Because you’re so technically proficient that you can take it to a place where faster and more complicated isn’t always better?

Yeah, that’s what I mean. Sometimes that’s cool, if the song calls for it. But if I end up starting to record for another album, I want to make sure I approach it the right way. — The New York Times