The music and fashion mogul, 33, is running the Nov. 2 New York City Marathon to raise money for several charities. He's being trained in part by three-time New York marathon winner Alberto Salazar.
SI: Why run a marathon?
COMBS: I woke up one day and said, 'Yeah, I'm gonna run NYC.' Life is like a marathon, and I'm going through a new phase in my life. I'm going to be the first rapper to represent hip-hop in a race.
SI: So, how did the 20-mile run you did with Salazar (right) on October 16 go?
COMBS: Incredibly. I hit a lot of walls, especially at mile 16 and mile 19 when my knees were hurting. But Salazar kept wanting to go harder. He helped me see that you have to be tough. If you ain't tough, you ain't made for the marathon.
SI: Can you finish 26.2 miles in under four hours?
COMBS: I'm going after Oprah Winfrey's time [4:29 at a marathon in Washington, D.C., in '94].
SI: Did you really run track at Howard University?
COMBS: Oh, yeah. I ran 400 yards.
SI: Don't you mean 400 meters?