After earning his degrees in exercise science and kinesiology from the University of Illinois-Chicago, personal trainer Tim Grover scored then Chicago Bulls star Michael Jordan as his first pro client in 1989.
Grover says he wrote a letter to every Bulls player at the time, but Jordan was the only one to respond.
"He gave me 30 days. Thirty days turned into 15 years," Grover wrote on Instagram in 2015.
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In his new book, "Winning: The Unforgiving Race to Greatness," Grover reveals what he's learned about what success looks like. As Jordan writes in "Winning," Grover "knows more than anyone about building winners."
Here's some of what Grover has learned about winning, no matter what the challenge.
'There are no steps'
Using inspiring quotes or trying someone else's step-by-step program for success is an amateur move, according to Grover.
That's because different motivation and processes work for different individuals. You need to figure out what works for you.
"There are no steps. I can't say, 'Here are the five steps to get into the zone,' or the '10 steps to success,'" Grover tells CNBC Make It.
"Those steps are infinite and they're constantly changing."
Jordan, for example, didn't have the same training routine as Bryant, and their individual routines evolved as their game did and as they did.
"I needed to prove myself over and over again because the routine I used for MJ is not the routine that I'm going to use for you," he says, because everyone has different needs.
Grover's advice: Experiment to find what works best for you, then constantly switch up your routine as you grow.
Winners see themselves as 'different'
"Winning makes you different and that difference is going to scare people," Grover says.
"People are not going to understand your work ethic. They're not going to understand why you do the things you do at the intensity that you do it and why you continue to want more and more and more," he says.
Grover says people who are true gamechangers don't think outside the box because they don't even see a box. "They see possibilities. They use their own decisions, successes, and failures as a springboard to elevate their thinking and results," Grover writes.
"Everyone wanted to be like Mike. Mike did not want to be like anyone else," Grover writes.
Grover's advice: "Winning requires you to learn, question what you learned, and then learn more. You have to be willing to challenge what you've been taught, and learn it again with a different perspective," Grover writes.
'Fear and doubt aren't the same thing' and the difference is crucial
"Fear and doubt aren't the same, and the difference is as distinct as winning and losing," according to Grover.
"Before every game, you'd see MJ alone, head down, chewing his gum, having a private conversation with himself. He felt the same nerves you might feel before you're about to face a challenge. But he never doubted that he would perform at his best," Grover writes in "Winning."
That's because when winners get fearful, they quiet their minds by thinking about all the preparation and work they've done to get where they are. They don't allow their fear to escalate into uncontrollable doubt, Grover says. They trust themselves to handle the situation or challenge ahead.
"Fear shows up on its own. Doubt has to be invited. Fear heightens your awareness; it makes you alert. Doubt is the opposite; it slows you down and paralyzes your thinking," Grover writes.
"Fear is about the threat, whatever you have to face. Doubt is about you."
Grover's advice: "For both MJ and Kobe, it all came down to a relentless belief in whatever they did," Grover writes. "Every decision, every move, was rooted in confidence."
With winning, your heart has less of a voice
Jordan said it all in his ESPN documentary "The Last Dance":
"My mentality was to go out and win at any cost. If you don't want to live that regimented mentality, then you don't need to be alongside of me.... And if you don't get on the same level, then it's going to be hell for you."
To win, Grover says you need to put your thoughts and desires ahead of your emotions and ahead of everyone else's emotions. People may call you "obsessed" or "crazy" or "difficult," he says. "But you are not the problem, you are the solution."
"The higher the pressure, the longer you fight to stay at the top, and the more you focus on this one thing, the less you allow your heart to have a voice in your decisions and actions. You don't have the luxury of being any other way," Grover writes.
Grover's advice: You have to accept others just might not get it and forge ahead regardless.