When Nate Ursel dives into Lake Nokomis on Saturday morning to begin the Life Time Fitness Minneapolis Triathlon, he will face a mentally and physically taxing journey toward a finish line he has crossed as a participant twice before.

Each time, he said, he has been motivated by a man who worked up the courage to cross that same finish line three years ago.

Brothers Nate and Alex Ursel had competed in short, indoor triathlon events before, so when the Life Time event in Minneapolis neared in 2010, they signed up and were excited, Nate Ursel said, about taking on “the real thing” together.

When race day arrived, a family emergency prevented Nate from participating. Alex Ursel carried on as planned, waking up at 4:30 a.m. to get to the check-in station on time.

Alex said he felt good after the 0.4-mile swim and the 15-mile bike ride. Only a three-mile run separated him from completing the triathlon and greeting his mother and brothers at the finish line.

But with a half-mile to go, Alex suddenly didn’t feel right, so he ran over to a tree on the side of the path. There, while athletes continued their races all around him, Ursel had what he would later discover was a seizure. Three weeks after the event, Alex Ursel found out an inoperable, golf ball-sized brain tumor was the cause of his episode.

Participants stopped to help him. One man gave him bottles of water, while another allowed him to use his cellphone so he could call his brother. The paramedics and Nate, who had arrived in time hoping to see Alex finish, hurried to his side.

Because he wasn’t physically injured, Alex Ursel didn’t require any immediate medical attention. After several minutes, Nate encouraged his brother to stand up and finish the race he started. Forty-eight minutes after he began his run, Alex Ursel crossed the finish line, his brother right behind him.

“Nate’s always been one who’s kind of challenging me to go to the next level on this or that or anything,” Alex Ursel said. “For Nate and me, it was kind of a gratifying moment to be able to do that together.”

Though the tumor is not aggressive, it prevents Alex Ursel from competing in strenuous activities for long periods. He takes medication daily and has to be careful about spending too much time outside in hot weather.

But in his brother’s diagnosis, Nate Ursel has found the source of his inspiration.

Nate Ursel, who calls Alex his hero, said he’s always looked up to his brother. Before his diagnosis, Alex, 34, of Blaine, spent four years in the U.S. Army’s 82nd Airborne Intelligence Unit and served in Iraq and Afghanistan.

Nate Ursel, 40, of Shakopee, has trained for and competed in the Life Time Fitness Minneapolis Triathlon each year since his brother’s 2010 finish. The training process hasn’t been easy, Nate Ursel concedes, but when he falters, one thing is sure to lift his spirits.

“There’s days where your body doesn’t feel right or your mind isn’t right or you’re exhausted or there are other pressing life things that are distracting,” Nate Ursel said. “I think there’s days like that where I think of my brother’s journey and realize that my legs can do what he can’t.”

Nate Ursel is one of more than 2,500 people who will participate in the different levels of the triathlon on Saturday morning. If he feels well enough, Alex Ursel will be out there supporting his brother.

But regardless of where Alex Ursel is on Saturday, he’ll be present in his brother’s thoughts.

“You never really think that highly of yourself, that you’re an inspiration for others or that anybody’s doing something because of you,” Alex Ursel said. “It feels good that somebody is inspired by what I’m doing, in my opinion, just living my life.”