Warren Buffett and Tony Robbins agree that the most important investment you can make is in yourself.
And when it comes to investing your money and saving up for retirement, Buffett and Robbins are also in sync: They both recommend investing in index funds. Especially if you're young and/or new to the market.
"Consistently buy an S&P 500 low-cost index fund," Buffett recently told CNBC's On The Money. "I think it's the thing that makes the most sense practically all of the time."