Your ability to manage stress and failure can make or break you as an entrepreneur. Alex Rodriguez has lived that struggle.

The 44-year-old slugger-turned-entrepreneur, who retired from Major League Baseball in 2016, is one of the most decorated baseball players in history. He's a primary investor in one of the fastest-growing companies in the U.S., fitness chain TruFusion, and a former Shark Tank guest judge. But he's perhaps most well-known for his year-long suspension from baseball for using performance-enhancing drugs.

Speaking at the 2019 Inc. 5000 Conference & Gala in Phoenix Friday, Rodriguez said that his year away from baseball transformed his mindset--and helped him understand what it takes to succeed in his business ventures today. "The suspension cost me north of $45 million, probably more," Rodriguez said. "It was worth every penny."

Rodriguez described his experience as a self-implosion that led to a lot of long, lonely nights staring into a mirror. Eventually, he said, he realized that he needed to stop fighting the allegations and start taking accountability for his mistakes. That meant calling his closest friends, family members, and business partners to apologize. "I thought these phone calls would take about two weeks," he said. "It took about six months to build the courage. I would pick up the phone and hang it up, pick up the phone and hang it up."

Every one of those phone calls, he said, resulted in stronger, more trusting relationships today. They also prompted a realization in his business life: Turbulence is an inherent part of entrepreneurship, and it never goes away. Success, he said, is defined by how you respond to that turmoil.

Rodriguez added that the epiphany has informed every one of his business decisions since he retired from baseball, especially when it comes to investing in startups: He looks for entrepreneurs who have a sound business strategy but also show a "winning spirit" and a tangible level of grit.

Rodriguez used a personal metaphor to illustrate the point: In addition to his 2009 World Series title and 696 career home runs, he's also fifth all-time in total career strikeouts. "Only four people in the history of mankind have more strikeouts than me," he proclaimed, eliciting applause and laughter. "I say that I have a PhD in failing, and a Master's in getting back up."