Legendary investor Jack Bogle said on Monday that the Federal Reserve did the right thing by not raising interest rates at its meeting last week.
"There are plenty of challenges ahead for our economy as the whole world economy gets into this messy state it's in," he said. "So I think the Fed is doing just the right thing under the old Hippocratic oath. First, do no harm."
Bogle, the founder of the world's largest mutual fund company, Pennsylvania-based Vanguard Group, spoke on CNBC's "Power Lunch."
Bogle described the U.S. economy as "adequately strong but not vibrant," citing wage pressure and a small workforce.
He also recommended investors to start saving for retirement and college as soon as possible.
"There is no other way to do it. You want to start building early, as early as you possibly can, because that slope gets steeper and steeper; the more money you have to put in per month the closer you get to retirement."
He added that investors should be happy when a market goes down because that offers cheaper buying opportunities.
"When the markets go way down, it's great for buyers and bad for sellers," he said. "Just ignore all the noise."
—Elizabeth MacBride contributed to this report.