Rashad Vaughn was ready to make a change.

Drafted in 2015 by the Milwaukee Bucks, when he was just 18 years old, he has spent the last two years closely observing his teammates and established veterans in the league. He wanted to make improvements.

But he needed to define exactly what those improvements would be.

“Once you get to this level, you realize it’s bigger than talent, skill,” said Vaughn. “It’s mental. That’s what you always hear, ‘The game is 99% mental’ — but they never really went into detail of what that means. So I’m thinking, ‘OK, I need to know all the plays. I need to know who I’m guarding.’

“But now, I know — especially being so young — a lot of your life is predicated on your thoughts. How you think. Things you say to yourself."

The 21-year-old guard concluded that making choices about his nutrition would fuel him and, ultimately, his career.

But changing the diet is hard.

Vaughn was so good at Findlay College Prep in Henderson, Nev., he could eat whatever he wanted. His favorite was the McDonald’s McGriddle and breakfast burrito.

“That’s what we liked, that’s what we lived for,” said Vaughn.

Then he got to the NBA and saw some of the best players, and the ones with the greatest careers, were talking — and preaching — about the benefits of stretching, fueling (not just eating) and rest. They took it seriously. Veteran guard Jason Terry even had his own water with a particular PH level and electrolytes.

“Before you know it, everybody was drinking that stuff,” said Vaughn.

Vaughn was ready to look at his own nutrition, so he brought along the Bucks’ in-house dietitian Shawn Zell to the grocery store with him to figure out what he should eat.

“And when he’s not with me, I go to the same aisles in the store and buy the exact same things he told me to get,” said Vaughn. “Same brand.”

Vaughn gave up eating pork and favorite treats like Honey Buns, Twinkies and Welch’s Fruit Snacks. (They're really just candy, with four teaspoons of sugar per serving. Fooducate gives the product a D+ grade).

He started looking for sugar alternatives and found Zevia. This company makes sparkling waters, soda substitutes and protein drinks with stevia, which is derived from a plant of the same name and considered by some dietitians to be a much healthier substitute for sugar.

Vaughn became a spokesperson for Zevia and spent one summer day with the company president and CEO, Paddy Spence, in Madison, talking nutrition as they watched the CrossFit Games.

Spence, a veteran of 40 triathlons and more than 100 road races, has had his own battles with sugar.

“Fifteen, 20 years ago, I thought I was healthy. I was doing triathlons, eating at Whole Foods and then I woke up one day and I realized I was getting 250 grams of sugar… from ‘healthy’ stuff,” said Spence. “Protein smoothies and energy bars, all this stuff was full of sugar. I would get these energy spikes and then I would crash.”

He and his wife secluded themselves in a cabin with no sugar and the nearest store 12 miles away. And they detoxed. Spence broke out into hives.

“The first two days I was laid out on the couch,” said Spence.

This story made a big impression on the wide-eyed Vaughn, and Spence believes that if Vaughn is serious about improving his eating habits at such a young age, he will reap the benefits forever.

“Exercise is cumulative, right? As you get older, you benefit from what you do,” said Spence.

“The diet is the same way. If you start at 20 with a clean diet, when you’re 50, you’re going to look like you’re 25. I’ve found, as I got older, that’s when diet made more and more difference.”

But again, change is not easy. There is temptation everywhere.

“You’re sitting on a plane or something and teammates are eating candy, and you’re like oh my goodness,” said Vaughn. “But without it, you feel differently. You feel better. It’s a big difference — and it gives you that edge.”

At media day to kick off the season, several Milwaukee Bucks mentioned they also had looked closely at changing their eating habits over the off-season.

And it helps to have outside support.

"I literally have nothing in the house. Like — nothing that’s bad or that I don’t want to eat," said Vaughn. "I live with my cousin and he’s like, ‘Man there’s nothing in here.’”

Nick Davis, 21, grew up with Vaughn. When Vaughn needed someone to rebound his shots, Davis was the guy. When Vaughn said he could use a wingman his rookie season, Davis packed his bags.

“Now that he’s on a health schedule, I’m on a health schedule,” said Davis. “I like to keep him on his diet and eating the right things and drinking the right things.

“If I have to go shopping for him, I will so he don’t sneak snacks and put it in his room. And I won’t eat certain things in front of him because he will want to eat that. If I eat candy in front of him, he’s going to want to eat candy.”

Vaughn and many of his teammates worked on their nutrition. Now with training camp open and the season looming, they're hoping to reap the benefits.

“It’s definitely making that sacrifice,” said Vaughn. “And setting a goal that you really want to achieve. It’s easier said than done."