This story is part of the Top of the Game series, where CNBC Make It delves into the habits, routines and mindsets that top athletes use to achieve peak performance and success.

"As a kid, I always dreamed of going to the Olympics," U.S. swimmer Ryan Murphy tells CNBC Make It.

Now at 26, Murphy is heading into his second Olympics, which kicks off in Tokyo with the opening ceremony on Friday. Murphy hopes to pull off a repeat of his success at the 2016 Olympic Games in Rio, where he took home three gold medals in the 100-meter and 200-meter backstroke and the 4×100 meter medley relay, during which he set a world record.

Murphy, who started swimming at the age of 4, says his passion began when his parents, Pat and Katy Murphy, moved the family to Jacksonville, Florida, from Chicago.

"To meet people [and because] the weather was super hot, we [went] to the community pool every day," Murphy says. "And then it just kind of progressed from there."

After swimming in high school, Murphy went to the University of California, Berkeley, where won both the 100- and 200-yard backstroke events at the NCAA Championships for four straight years, among other awards. He balanced 30-plus hours a week of practice and competitions with studying, maintaining a 3.54 GPA at the Haas School of Business.

"I do consider myself a little bit of a nerd," Murphy says, adding that he loves to watch the stock market on his days off.

After graduating in 2017, Murphy turned pro.

To reach peak performance, Murphy says he puts a lot of time into learning about things like nutrition, sleep and recovery. And something as "simple as balance," he says.

That's important because being an elite athlete isn't easy, Murphy says. "It can be lonely. There's a lot of work that goes into trying to be the best."

Here, Murphy talks to CNBC Make It about his mindset and routine heading into the games in Tokyo and how he gets through the tough moments.

The moment he knew he was ready for the Olympics

Watching the 2000 Olympics, I was a little 5-year-old kid at that point, and I just kind of knew at a young age that I was really passionate about swimming. And that passion took hold.

Personally, I started to believe in myself at the 2012 Olympic trials. I was 16 and I got fourth and sixth in the 200m and 100m [backstroke] races. That was kind of a big breakthrough for me. I dropped a lot of time and it was the first time I was able to get into "big boy" heat and race some of those older guys.

So, at that point, I was like, all right, I think I've got a shot at this next time around, and I really kind of put my head down and work towards that goal.

Olympic training routine: Doubles three days a week, and high intensity

I train at Cal [at the university's facilities] year-round in Berkeley. Everyone on Team USA trains at different locations. 

We have doubles on Monday, Wednesday and Friday: We're in at 6 a.m. to 8 a.m. and then we're in again from like 12:40 p.m. until 3:50 p.m.

Since those days are a lot of work, after that morning practice, I come back, make an omelet, take a nap and then get up and get ready for the afternoon practice.

After the afternoon practice, it's really a lot of focus on recovery.

But our Tuesdays, Thursdays and Saturdays are probably our hardest practices. Those are really high-intensity, really high-quality, pretty much empty the tank on all three of those days.

So, I'm doing a lot to try to prep my body to be ready for those practices. I'll be laying on a lacrosse ball, foam-rolling and stretching to make sure that I'm doing everything I can to have my body in a good position.

Sunday is my day off each week, so that's when I'll do things like golf, watch football and hang with friends.

What Murphy eats before every swim meet

Ever since I was started swimming when I was 4, my mom always made me a peanut butter and jelly sandwich before we went to the pool and I've kept that up. I'm 26 years old and I make peanut butter and jelly before every swim meet and before every session.

Another thing about my routine that's maybe a little over the top is that I make a vegetable smoothie every day. It doesn't taste very good. But it is honestly probably the most healthy thing that I eat. I will throw in spinach, carrots, broccoli, beets, some cherries, coconut milk or almond milk and a little bit of coconut water. If I'm feeling good, I'll throw in some cinnamon in.

I probably eat around 6,000 calories a day when we are in really hard training.

Saturday night I will typically have my cheat day, which is typically a ribeye and after a really good dessert. I'm a big sucker for chocolate ice cream.

Dealing with the pressure before a big competition

I love to listen to music right before the races. It definitely pumps me up or settles me if I'm super nervous.

One of my strengths as an athlete is that I'm really good at downplaying the super-high-pressure moments. One of the things that I believe is, the best way to deal with pressure is to deal with pressure.

So, I try to make sure that I put a lot of pressure on myself in situations that I don't really call for it so that when I get to a big stage where there is naturally a lot of pressure, I feel like I'm prepared to handle it.

As we get closer to those big meets, I do try to put aside the time every day to meditate.

What Murphy thinks about when swimming

When I'm competing, I'm really pretty dialed into a race strategy. That's something that I think about in the weeks leading up to a meet. Obviously, I will kind of look around at other competitors and get a little bit of a motivation boost, but essentially, I'm really thinking about the race strategy and trying to execute that as best as possible.

For the longer races, I can definitely get into a nice rhythm and that just feels good. That's the easy part of the sport.

But there's a lot of times where you'll get into a race and things just don't feel perfect. And then it's like, all right, how am I going to compensate for something that doesn't feel good here? How am I going to make my technique a little bit better? How am I gonna push off the wall and all that sort of stuff?

How he handles defeat

I learn a lot from the losses or when I'm disappointed in a race.

[After a loss], I take a week after those competitions and just try not to think about it. I let myself settle down a little bit emotionally.

Then I'll kind of go back and write down some things and try to have a really honest conversation with all the people that are supporting me. I'll talk to the coaches and ask, "What's on me? What do I need to do better?" I'll also come in with some things that I think I can do better.

We have to have an honest conversation and try to keep the emotions out of it. Because, at the end of the day, we're on the same team.

Finding swim-life balance

I put a lot of time into learning things like nutrition, recovery, sleep. But it's very easy to kind of become a robot and just get so intense towards your sport, so you also need to have time for yourself. You need to have time to relax and do things you enjoy.

There are definitely times in the year that I'm able to go and do the traditional 26-year-old fun activities. But as we get closer to the big meets — for example, this summer — I won't have a sip of alcohol before the Olympic Games or [at] Olympic trials. But I'll get together with friends and we'll go for a golf round or they'll come over we'll watch the NBA Playoffs. 

The emotional toll of being the best

It can be lonely. There's a lot of work that goes into trying to be the best, but I'm super fortunate to have a group of people around me that understand that.

They also understand that they are going to have to put on a lot of different hats. They're going to have to be someone that will be supportive, and they are also going to have to be kind of [my] psychologist. There's a lot of times during the season when you're overtraining, you're broken down [and] you're not optimistic about why you're doing this. And those people have to kind of pick you up and say, "Look, you've put in a lot of work and you're gonna get broken down, but it's worth it."

This interview has been edited for length and clarity.

Disclosure: CNBC parent company NBCUniversal owns NBC Sports and NBC Olympics. NBC Olympics is the U.S. broadcast rights holder to all Summer and Winter Games through the year 2032.

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