Teenagers are often preoccupied with getting good grades, preparing for college and having fun. When Justin Fong was 14 years old, though, he was attending his fourth consecutive Berkshire Hathaway annual meeting as a shareholder. At the 2004 meeting, the California teenager had a question for Berkshire Hathaway CEO Warren Buffett and vice chairman Charlie Munger. "I read in a book that you prefer talking to young people about life and financial concepts because we still have time to implement them," Fong said. "Can you please share some of the concepts with us?"

Buffett responded by noting that he actually does enjoy spending time with young people and answering their questions. Here are the three pieces of life and financial advice Buffett and Munger shared with the teen shareholder.

Form good habits — now

Don't wait until you're too old to start good habits, Buffett advised: "Young people are more receptive to change or actually at even forming habits that are going to be useful in life."

"I think that people underestimate, until they get older, they underestimate just how important habits are," Buffett said. "And how difficult they are to change when you're 45 or 50, and how important it is that you form the right ones when you're young." Munger recommended turning bad experiences into life lessons. "You want to develop a good character and good mental habits, and you want to learn from your mistakes, every single one, as you go along," Munger said. "It's pretty obvious, isn't it?"

Don't get into debt

Buffett understands the appeal of taking on debt, but the billionaire said it's just not worth it. "It's very tempting to spend more than you earn, it's very understandable. But it's not a good idea," he said. People often wrote letters to Buffett explaining "all kinds of financial trouble" that they are in because of debt. Buffett wrote back to them, he said, because "they are very decent people" who have "just made mistakes." "I just tell them the best course is bankruptcy. I mean, they are not going to catch up. And they should start all over again, and they should never look at a credit card the rest of their life." Buffett's bottom line on debt: Avoid it if you can. "Even though we issue lots of credit cards and everything, we'd say, probably, if I had one piece of advice to give to young people, you know, across the board, it would be just to don't get in debt," Buffett said.

Surround yourself with good people