Kate Grace is an Olympian for the first time. (Patrick Smith/Getty Images)

Every now and then over the past six months, doubt would creep into Kate Grace’s mind. It would happen unexpectedly when she was in her car or participating in workouts, causing Grace to question herself during one of the most important seasons of her professional running career.

And each time Grace countered those thoughts with the same three words. “I’m an Olympian.” She would repeat it aloud to herself. “I’m an Olympian.”

At the U.S. Olympic track and field track trials Monday, those words became reality as Grace claimed first place in the women’s 800-meter final in Eugene, Ore., to qualify for the Rio Games. Few people predicted Grace would make the team, let alone win the race, but the victory was just another triumph in a season filled with personal bests for the self-proclaimed underdog.

“It hasn’t been one race that’s been necessarily the biggest surprise,” Grace said Wednesday in a phone interview. “It’s been just a slow, gradual snowball of a momentum effect of a good training followed by good race, followed by good training, followed by good race. It’s been a good feeling, and it’s made me very confident.”

The result was aided by a collision that caused the fall of two favorites, Brenda Martinez and Alysia Montano, clearing the way for Grace to power through in 1 minute 59.10 seconds, a personal record. The top three in each event qualify for the Olympic team.

In the hours leading up to the the race, Grace’s coach, Drew Wartenburg, advised her to be patient and stay on the inside of Lane 1, where there is less exposure to other runners. It proved to be prescient advice.

“I was prepared for it and I’m proud of how I raced,” Grace said, while also adding that she feels “deeply” for Martinez and Montano because of the respect she has for them. “So in that sense, the way the final unfolded does not take away from the pride.”

The race also marked the first national title for the 27-year-old Grace, who graduated from Yale in 2011 as an all-American. She had a breakthrough season in 2013 under coach Frank Gagliano at the New Jersey-New York Track Club, but posted inconsistent results while struggling with injuries the following seasons.

Grace joined Wartenburg and the NorCal Distance Project in Sacramento last July coming off a foot injury in a move that brought the Los Angeles native back to the West Coast. The structured environment allowed Grace to have a consistency in her training and resulted in several impressive victories against more accomplished and well-known runners.

In mid-May, Grace ran through the pouring rain in Portland to take home the 800-meter title in one of the deepest races of the night. A few days later, Grace finished first in the 1,500-meter race with a personal best of 4:05.65 against a stacked field that included Olympian Shannon Rowbury, the American record holder in the distance.

The change in success started in practice. Earlier this year while training in altitude in Flagstaff, Ariz., Grace endured one of the hardest runs she’s ever experienced — 13 miles at a 6:20 pace. These are the type of workouts a middle-distance runner like Grace normally avoids, but instead of fearing it, she attacked the workout, refusing to let teammate Lauren Wallace out of her sight.

“I’ve done a lot of work mentally to how to really want the pain in the workouts and really want the level of hurt in workouts, because that’s the point where you’re improving,” Grace said. “I’ve worked harder in workouts this year than I ever have in all my life.”

Grace opted not to race in the 1,500 at the trials as she has already qualified for the Olympic team and does not want to go through the emotional and physical toll of potentially racing multiple rounds.

“It would be fun, but the risk analysis is that it would not be the smartest call,” Wartenburg said.

Wartenburg has marveled at Grace’s development in the past year.

“As a coach, I make sure I’m as prepared as I can be,” he said, “but Kate looks at every possible angle and prepares as fully to the necessary degree without overdoing it. She’s grown a lot in terms of self-awareness.”

And as she heads into Rio, Grace knows there will be doubters – this time on the outside, questioning whether she truly deserves to be on the team. For Grace, this will just give her another opportunity to embrace the underdog mentality.

“I feel very confident in my fitness and it’s like, now I get to show the world what’s behind the door,” she said. “That race was one step in proving people that I should be on our list and there will be many more. And I’m looking forward to Rio being more races like that.”