Motley Fool co-founders Tom and David Gardner have both put up exceptional long-term track records, and in a recent interview with WealthTrack, Tom discussed the brothers’ investment philosophy. Gardner says that the biggest thing an investor can do to improve their chances of success is extend their time horizon. He also says that, while the Fool offers a number of different approaches and portfolios, all of them center on the concepts of focusing on the business, not technical factors or short term stock movements, and thinking long-term. He talks about why it’s important to diversify, and why his value approach has been less volatile than his brother’s growth approach but has delivered lower returns over the long haul. Finally, Gardner talks about why he thinks index fund pioneer Jack Bogle is wrong in saying that the average investor can’t beat the market, and why he thinks Starbucks is currently one stock that can help them do that.