Warren Bufettf & Ray Dalio Advices

"You've got to do the opposite," Dalio said. "It's when you're not scared you probably want to sell and when you are scared you probably want to buy.

"The greatest mistake of the individual investor is to think that a market that did well is a good market rather than a more expensive market. And that a market that did badly is a worse market ... rather than a cheaper market," he explained.

"We spend hundreds of millions of dollars a year to get an edge, and others do that too," Dalio said, referring to Bridgewater, which manages about $160 billion. "So it's very difficult for the individual investor to assume that he [or she] can pick something better."

Instead, create a diversified portfolio and hold steady, advised Dalio. "The best thing you can do is know how to have a balanced portfolio ... because you ain't going to win that game."

"That was very valuable advice that if you can discipline yourself and your relatives to follow over the next substantial number of years will be worth a lot of money to you," he said.

Buffett emphasized that holding onto investments long-term is crucial to having them pay off. "The money is made in investments by investing and by owning good companies for long periods of time," the Berkshire Hathaway CEO told CNBC. "If they buy good companies, buy them over time, they're going to do fine 10, 20, 30 years from now."

He continued: "What investors then need instead is an ability to both disregard mob fears or enthusiasms and to focus on a few simple fundamentals. A willingness to look unimaginative for a sustained period — or even to look foolish — is also essential."

Dalio, the founder of investment firm Bridgewater Associates who is worth an estimated $14.6 billion, agrees. Though it's tempting to sell when the market begins to drop, he says, giving in to your fear is not a sound strategy.

"You can not possibly succeed that way," Dalio said at the Harvard Kennedy School's Institute of Politics. "You've got to do the opposite. It's when you're not scared you probably want to sell, and when you are scared, you probably want to buy."

Both investors say that the best way to invest successfully is by not trying too hard to anticipate market fluctuations and by staying calm despite them.

Coutersy of CNBC.