Carl Lewis, one of the most accomplished Olympic athletes of all time, never liked running. “I was a sprinter, not a runner,” says Mr. Lewis, who competed in four Olympic Games and won nine gold medals in the 100-meter, 200-meter, 4 x 100-meter relay and long jump events. “I don’t ever run anymore,” he adds.

Mr. Lewis does, however, still jump. At 54 years of age, Mr. Lewis says tumbling, trampoline and trapeze work have helped him maintain his fitness. “I’m not as lean as I was but I feel as good as when I retired in 1997,”...