Jim Ryun was going for the gold in the metric mile at the 1972 Munich Olympics. In his semifinal race, he got tripped up and fell with about two laps to go. He got up and ran valiantly, but he could not catch the leaders and didn’t make the final. He just didn’t have enough time to make up the difference and ultimately didn’t get a shot at the gold.

Are you familiar with the Rule of 72? It’s a shorthand way of calculating how long it will take for your money to double. Take an interest rate—say, 7 percent. Divide 7 into 72, and that’s a little over 10. That means it will take a little over 10 years for your money to double at a 7 percent rate of interest.