...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."
...In his annual shareholder letter, Buffett explained that the markets are always going to be volatile, so the best thing any investor can do, regardless of experience, is to keep a level head. "
Though markets are generally rational, they occasionally do crazy things," he wrote. "Seizing the opportunities then offered does not require great intelligence, a degree in economics or a familiarity with Wall Street jargon such as alpha and beta."
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."