According to the Gallup Poll, 24 percent of American adults exercised regularly in 1961, and 50 percent after 1968. The peak was 59 percent in 1984, dropping off to 51 percent last September.

After 26 years, I am still practicing what I preach.

America's got a Darwin problem - and it matters. According to a 2009 Gallup poll taken on the 200th anniversary of Charles Darwin's birth, fewer than 40% of Americans are willing to say that they 'believe in evolution.'

I have not missed a day from work because of illness since 1956.

You have to run 75 to 100 miles a week if you expect to break the four-minute mile.

I used to think that it didn't make any difference how far you ran if you had a good, strong musculoskeletal system and no underlying cardiovascular problems.