During a recent interview, Rick Rubin, the co-executive producer on Eminem's recently released eighth studio album "The Marshall Mathers LP 2," spoke about the rapper's latest effort.

"I would say that he is probably the most obsessive artist, maybe, that I have met in any genre," said Rick Rubin. "He is very, very dedicated to his craft. To the point to where it seems like there is nothing else in his life. It truly is a 24-7 thing for him. One of the reasons that many artists make good records when they're young and then as they grow up, maybe they're not doing their best work anymore, is because - especially if you're successful - other things in life take over. Whether it's family life or just other interests. It just happens.

"When you make a record when you're 19 and then you're making a record when you're 40, usually when you're 40, there are other things in your life that are more important than music by that time," Rubin continued by saying how the rappers' attitudes toward music usually change over time. "When you're 19, it might be the most important thing in your life. I would say Em is unusual in that he's a grownup, who is as dedicated and focused on music as... I can't imagine he was ever more so at any other time because it's full-on all the time, 24 hours a day. Whether he's working on a record, not working on a record, he's writing all the time. Full time.

"We were just talking about it the other day," Rubin added. "He said, 'I write constantly, to the point where while I'm writing in my books, I know 95 percent of this stuff, 98 percent of it's never gonna get used. But by writing all the time, it's like I'm sharpening my tools. And I'm more able to draw upon that skill-set when needed. And sometimes, a reference that I wrote two years ago might come back and find its way into a record completely unrelated, just because I was doing this homework and coming up with a new rhyme scheme or just hearing a word I liked and thinking about how that could rhyme. And there might not be any context for it. But then I might be working on a song years later and think, 'Oh, maybe that phrase could work in this context.' ... And it's like that always. There is no time off. And it's really unusual. I've never met another rapper like that, who is so on. So on and so obsessed. It's number 1 in his life. Period. That's it."

The acclaimed producer also discussed his work with Eminem in the studio.

"I collected up lots of possible ideas of staring points," said Rick Rubin. "A lot of samples and a lot of beat ideas and I'd play him a bunch of stuff and just say, 'Tell me which of these feels like a good starting point.' And then he would pick a bunch of them and then we would develop each of those a little bit. And then he would listen to them and say, 'Okay, these are the ones I want to work on.' Then he would take them to write and then we would find more stuff.

"We worked like a tag team," he continued. "We had two rooms set up at the Shangri-la Studio in Malibu. In one room, we were building beats and in the other room, he was doing vocals. Anytime he would have a vocal thing together, he'd bring it in and play it for me, and we would talk about it. Anytime I would have a new version of a beat or change in a beat or further developed a beat, I would call him in and he would listen to it and say what he liked and what he didn't. We just kind of worked together, back and forth."