I couldn't disappoint people. I did not want to fail and exhaust myself, because I was the kind of runner who trained so little that I couldn't race again within another 10 days.

We run, not because we think it is doing us good, but because we enjoy it and cannot help ourselves...The more restricted our society and work become, the more necessary it will be to find some outlet for this craving for freedom. No one can say, 'You must not run faster than this, or jump higher than that.' The human spirit is indomitable.

My introduction to track racing was through the background of cross country running, which is not a sport perhaps as popular in America as it is in England.

I came from such a simple origin, without any great privilege, and I would say I also wanted to make a mark. It wasn't until I was about 15 that I appeared in a race.

Whether we athletes liked it or not, the 4-minute mile had become rather like an Everest: a challenge to the human spirit, it was a barrier that seemed to defy all attempts to break it, an irksome reminder that men's striving might be in vain.

When I was about to break a world record and become well known, my mother used to say that for her the important thing was for me to become a doctor - a career which had not been possible in her generation and in her society. Sport was something to be set aside.

It is a paradox to say the human body has no 'limit.' There must be a limit to the speed at which men can run. I feel this may be around 3:30 for the mile. However, another paradox remains - if an athlete manages to run 3:30, another runner could be found to marginally improve on that time.