American Greek - its the greek genes that give him the endurance I reckon- look at YDT!!
I've just finished this book - a pretty good read and I thought his bragging was quite restrained (for an American). Not sure how he finds time for all the windsurfing and stuff that he says needs 400 press ups a day, even on 4 hours kip a night.
I especially liked the bit about adding a marathon on to the end of a 200 mile run!!!
Wonder how he'd get on with a BGR/PBR/RR....
Mike Stroud's book is next after "running through the wall" - picked up a handy collection of books on long distnace runing for christmas (wife's trying to tell me something...)