The irony of investing is that people often feel most comfortable buying stocks when the market is "high" and expensive. They see others growing assets and do not want to miss out. That's fine. One of the most valuable--and most often ignored-- pieces of investment advice is that you cannot time the market. While historical performance does not guarantee future performance, since 1926 the S&P 500 stock index has delivered an average return of approximately 10%. Instead of sitting on the sidelines, waiting for the "perfect" moment to invest, it is best to get in and start participating in the growth of the American economy and world markets.