But there's more than being a record setter to becoming an Olympian.

Her mother, Jeni Shimizu, said her daughter has learned how to stay focused on reaching goals and has come to appreciate the sacrifice it takes to become a world-class athlete. Pilar Shimizu has had to forego opportunities to spend time with teenage friends or attend family events as she focused on her training in the hope of pursuing her Olympic dream.

"I don't really feel like a teenager," Pilar Shimizu said, pointing to the two hours of practice she goes through daily.

But that doesn't mean she's been spared the typical teenage challenges. In addition to the pressure of training for the Olympics, she also faces other challenges, she said, like "enduring all the mental and physical blocks that this sport has given me, as well as growing up and maturing, all those problems that a teenager faces."

"These are the years that kids spend a lot of time together," Jeni Shimizu said. "Your middle school and high school years, going to movies and parties, she has had very, very little of that. And she craves that just as much as the next kid. And then there's family time, going to life events like christenings and graduations. On her training schedule, there are always these hard choices to make."

Add to that the workload of a high school honors student who wants to study pre-med in college, and the question of commitment becomes one that separates champions from all the rest.

"I just did what I could with the energy that I had, and I tried my best," Pilar Shimizu said.

The teen's shot at the Olympics took shape two years ago at the 2010 Oceania Swimming Championships in Apia, Samoa, where she set two personal best times and medaled in the 100-meter breaststroke. Shimizu's medal also brought accolades for Guam because it marked the first time anyone from the country medaled at an Oceania championship.

Jeni Shimizu said it took two years for "the next door to open" as her daughter crossed the daunting barrier between an Olympian and being just another good swimmer.

"At a certain level, cutting time becomes challenging," she explained. "You have to add on more training, you have to change training, you have to do a lot of things to chip away and become better.

"So these last two years I can imagine have been very hard for her. She's had to take control of her training career and be fully involved in the changes being made, and be committed to it. That's where she's at right now."

Pilar Shimizu admitted that the last two years were a period of transition as she realized she had to become more focused and more efficient in her swimming strokes. She said she still has room to improve and has set a goal to swim the breaststroke in less than 1:14.

She said her older brother, Carlos, who also swam competitively in high school, helped her "realize how big of a deal the Olympics were. He put that dream in front of me."

Pilar Shimizu's father also helped her by being the one who was "always super chill," she said. He was the comforting factor when the road to the Olympics would become particularly stressful.

But it's her mom, she said, who pushed her to stay on track: "When I absolutely want to quit, she helps me by not giving up."

"Pilar could be at a very low point," Jeni Shimizu said, "but if you ask her if she wants to quit, she would always say, 'No.' The worst part was 'I don't know.'"

It was in those moments of uncertainty that her mother pushed on.

"I asked her permission, 'Since you don't know, may I have your permission to keep you on it?'"

Pilar Shimizu's response is evident in the Olympic slot she holds today.

"I just never gave up with her," Jeni Shimizu said. "Other people did because she just made it very difficult for them. But I just never gave up on her. Through it all she never said she wanted to quit. And that's the reason we kept encouraging her."

Having just turned 16, Pilar Shimizu's best is taking her to London to compete against the world's top swimmers.

"As a mother you see your child grow, you see where they shine, how their talents bud and start to develop, and this is an area of several areas that she seemed to have a knack for," Jeni Shimizu said. "But it really only took her until recently to accept that and use it.

"You do so much as a parent," she added. "You lecture them and you try to teach them. And you just don't know if they're listening to you."

Evidently, Pilar was listening.

"She put on Facebook something about your talent is God's gift to you. What you do with it is your gift to God," her mother said. "There's this ongoing discussion in our family about ministering to your gifts in every form. The test of fully realizing your talent is when other people around you in some way are blessed by it."