Vanguard Founder Jack Bogle has some simple advice for investors: Invest — and don’t peek.

“Nothing,” Bogle tells Canada’s Globe and Mail when asked what keeps him awake at night. “Just invest, and don’t peek. Don’t open your retirement plan contribution statements every quarter. Put in money regularly, and when you retire 40 or 50 years later, and open the statement for the first time, you run the high risk of heart failure — you’ll be stunned at how much money you have accumulated.”

Bogle says investors should ignore the volatility of the stock market, which could be higher than usual in the coming years “given the mess that we have in our financial system.” He says the true value of stocks isn’t their price in the market, but the amount of earnings and dividends they produce. “The secret of making money is to own corporations that grow,” he says.

Bogle says he has all of his money invested in the U.S. markets, where he thinks stocks will significantly outperform bonds over the next decade. He also says he’s “very optimistic” on Canada, which has “many of the characteristics of the U.S. — strong capital markets and solid governments that are not going to be overthrown tomorrow.”