So I've broadened the fitness concept to make it one of moderation and balance.

We are involved in youth testing internationally. We want to try to prove without a shadow of a doubt the relationship between physical fitness and health, not just physical fitness and ability to perform.

Now I say that if you run more than 15 miles a week, it's for something other than aerobic fitness. Once you pass 15 miles, you do not see much further improvement.

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.

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.