Joseph Gray knows what it takes to be a world-class mountain runner. Miles, miles and more miles. Then, when he thinks he’s done, a few more miles for good measure.

Gray, 28, recently moved to Renton and is one of the world’s best runners. He’s represented the United States on 11 world teams, won more races than he can count and took 14th at the World Mountain Running Championships in Italy earlier this year.

Then, just this Sunday, he won the men’s 25-29 division at the XTERRA Trail Running World Championship at Kualoa Ranch in Kaaawa, O’ahu (Hawaii) in a time of 1:21:58.

He also tied with Ben Bruce of Flagstaff, Ariz., to win the overall World Championship title in XTERRA’s closest-ever race.

It’s the first time he’s won a trail running world championship title.

Gray has been a threat at the mountain running championships since 2008. Since then he hasn’t finished lower than 16th and has come in as high as 10th.

He went to high school in Lakewood, where he ran cross country and track in high school. He earned a running scholarship at Oklahoma State University, where he qualified for nationals four times in cross country and twice in track.

After graduating he started running professionally, but it wasn’t easy early on.

“I was improving in college, but I wasn’t the guy who was a national champion,” Gray said. “So the big companies aren’t going to come after you right away.”

So Gray found a couple of smaller companies that would lend him some support and went down the trail of trying to work and run professionally.

“At that point you either get better or you get worse,” he said. “If you get better, you can start demanding more things.”

He got better. Gray is now sponsored by Scott Sports, Mio Global, Garden of Life and Club Northwest, and is able to run full time.

Even runners at Gray’s level can get sick of it. At the World 50K championships this year, Gray was having a tough time with the hot weather and the repetitive loop course.

“It got to a point where I was just sick of it,” he said. “Mentally it starts to wear you down. But you just have to work through it.”

Gray’s training weeks include anywhere from 60 to 120 miles of running. That’s running every day, often more than once. And it’s something he’s hoping to carry on as long as possible.

“It will always be a part of my life,” he said. “As far as professionally, if I’m 45 and a company wants to sponsor me, then I’ll do it.”

After running, Gray is interested in working for the United States Anti-Doping Agency.

“It’s important for youth coming up to know that it’s not OK to dope,” he said. He also said his experience as a pro would give him an edge.

“I know how other athletes are slipping through the cracks. I’m around them and I can see what’s going on. I’m not blind.”