The idea had been percolating in Justin Grunewald's mind for some time. Though his career as a Gophers cross-country and track athlete didn't go quite as he hoped, he didn't lose sight of his long-held goal to compete in the U.S. Olympic marathon trials.

Grunewald made the cut for the 2012 trials in a half-marathon two years ago, just as another lifelong ambition had begun to complicate things. As a medical student at Minnesota Duluth, he struggled to fit training into a heavy workload of classes and studying. That only got tougher when he began doing rotations in two Twin Cities hospitals last summer.

Shortchanging either of those pursuits was out of the question. Last fall, Grunewald chose to defer one dream, if only briefly, to devote himself fully to chasing the other. During a four-month leave from medical school, he has trained full-time toward Saturday's Olympic marathon trials in Houston, which will determine the three men and three women who will represent the United States in this summer's London Olympics.

About two dozen Minnesotans will run in the trials. Some, including Team USA Minnesota's Jason Lehmkuhle and Katie McGregor, are in the hunt for Olympic berths. Grunewald is among the many who simply hope to run well in a race that will be the most prestigious of their lives.

"I'm living the life of a pro runner for a few months," said Grunewald, 26. "Come February, I'll start back up with an endocrinology rotation at Fairview University [hospital] and go back to the other life. I'm a little nervous, but mostly, I'm excited. You put so much effort in over the years that to actually reach your goal means a ton. So now, it's just go out there and see what you've got."

A posse of 10 relatives and friends is traveling to Houston to cheer Grunewald along the 26.2 miles. That includes his girlfriend, Gabriele Anderson, a professional runner who is among the top U.S. women in the 1,500 meters.

Anderson, who also ran at the U, said she was a little surprised that Grunewald qualified for the marathon trials in his first attempt. Athletes could earn entry into the trials by meeting time standards in the marathon, half-marathon or 10,000 meters, and Grunewald's personal-best time of 1 hour, 4 minutes, 50 seconds at the 2010 Houston half-marathon bested the standard of 1:05. Once he qualified, though, Anderson was not surprised at how diligently he prepared.

"He makes me feel lazy," she said. "I've never met a harder worker than Justin. If I tried to do what he's done, I'd be a terrible failure. His commitment shows how much he loves this sport."

A native of Brainerd, Grunewald was part of a Gophers cross-country team that finished eighth at the 2007 NCAA championships. But he tended to overtrain, he said, which led to injuries. He finished his college career feeling he hadn't reached his potential, and that he might be suited to longer distances.

At UMD, Grunewald arose every weekday at 6 a.m. for a morning run, attended classes and studied from 8 a.m. to 8 p.m., then got in an evening run. Even that schedule became untenable last summer when Grunewald began his rotations, working with attending physicians at Hennepin County Medical Center and the University of Minnesota Medical Center.

"I quickly realized it's not possible to run and be in surgery for 16 hours a day," he said.

"I'm going to be a doctor, but I only have so long to run. I wanted to give myself a chance."

Grunewald sought advice from Dr. Bob Kempainen, a professor of medicine at the U and a two-time Olympian in the marathon. Kempainen had taken breaks from medical school to train for the Olympics, and he suggested Grunewald take a leave to spend three months training for the trials.

That allowed Grunewald to bump up his mileage and sleep 10 hours a night -- twice his usual allotment. He ran a marathon in the Cayman Islands last month to get used to the distance and won in a course-record time of 2:36:23.

Grunewald's personal best in the marathon is 2:32:58, set at last year's Houston Marathon on a sweltering day.

The top qualifier for Saturday's trials, 2008 Olympian Ryan Hall, has a best time of 2:04:53. A top-20 finish would satisfy Grunewald, who plans to spend the next two years focusing on medical training.

That doesn't mean he's done with running. He will help Anderson prepare for the Olympic track and field trials in June, and he expects to run local races, though not with the same zeal he's putting into this one.

"Always, in the back of my mind, my dream was to run in the Olympic trials," Grunewald said.

"Deciding to give it a go while I was in med school, I don't know if that was a good idea or not. But it ended up working out."