I passed a copy of his autobio on to the local used book store some time ago.
If memory serves me right Clayton was fundamentally a 1500-meter trackie wannabe who just happened onto the longer distances and found some success, then just grabbed the comet by the tail and ran as hard as he could.
He had six sugeries on achilles and knees. He was frequently subject to colds and flu. I recall one line in the book were he 'dreaded' talking to people who were sick as he almost infallibly would take ill himself shortly afterward (a sign of overtraining: an overtaxed and weakened immune system). Also suffered from black urine, after one of his WR efforts.
He had a job as a civil engineer or draftsman, I don't recall 100% correctly which. He had a family, too.
He distinctly warned beginners NOT to follow his trail as he paid the price.
A Sports Illustrated interview (1970?) went like this:
"it's bloody boring at best and painful at worst but I very much want(ed) to be the Best in world at something"