Ex-NFL player and four-time Super Bowl winner Rob Gronkowski is known for his talents on the field, but the former New England Patriots star is now showing off another skill: investing.

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Considered one of the greatest tight ends in history, according to Fox Sports, Gronkowski recently revealed how he turned a $69,000 Apple investment into $600,000. Here’s three things you can learn from his investing approach.

In an interview with Fortune, Gronkowski revealed he didn’t know much about stocks, but at the persistent advice of a contractor who built his Foxborough, Massachusetts, home, he invested in Apple.

“Every time I saw him, when we were building the house, he kept saying, ‘Get Apple. Get Apple,’” Gronkowski said.

Gronkowski was 25 years old at the time and said he “really didn’t know how stocks work,” but he took the advice and decided to “go big.” He bought $69,000 of Apple stock.

Investing in stocks is always a risk. The economy could take a turn for the worse, a company could experience financial woes, a stock could lose value and more. Gronkowski took a chance by investing in Apple when he didn’t know much about the market, investing or knowing how solid the advice was, but it paid off.

When Gronkowski invested, he was four years into his football career and making millions, so it was likely a risk he could take, but there was still uncertainty — especially since he didn’t understand stocks at the time.

If you are considering stocks, Eric Mangold, CWS founder of Argosy Wealth Management, suggested being okay with losing.

“Do your research and be prepared to ride the ups and downs while not getting too emotionally attached,” he explained. “Also, make sure you understand how much you are allocating to one particular stock. Is this ‘play money,’ meaning if the stock tanks, are your bills still going to be paid?”

Although investing is inherently risky, you can mitigate that risk by not investing more than you can afford to lose.

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Gronkowski invested over 10 years ago, but actually forgot he put money into Apple. When he remembered, two years later, his investment had grown significantly.

“Now to this day, I have over $600,000 in Apple stock, all because of the investment I made in 2014 having no idea what I was doing, but just listening to the guy that built my house here in New England,” Gronkowski explained.

While Gronkowski’s method in this case was unintentional, it’s typically advised to hold onto stocks rather than sell quickly. Warren Buffett, who is considered one of the all-time greatest investors, firmly believes in this strategy.