As Americans are barely getting by due to inflation, tariffs, and a cost-of-living crisis, saving for retirement can feel like the priority lowest on the totem pole.

But multimillionaire serial investor and entrepreneur Kevin O’Leary says saving is more important than ever before.

“What piece of advice do I give my kids over and over and over again about money?” the Shark Tank star questioned in an Instagram video earlier this year. “Don’t spend it. Save it. Invest it. Let it compound. That’s the gift the market gives you.”

O’Leary’s golden rule of investing is straightforward. He says to take 15% of every dollar you earn, whether it’s from your paychecks, side hustles, or birthday money from grandma, and put it directly into the market.

“Just let it compound,” he said.