Peter, I believe in that also. It is a mind over matter thing. Or, one can say destiny, but the belief has to be there that it is destiny.
"Just do it" is more than a slogan of marketing in the world of athletic competition. It is a matter of 'see it', 'believe it', 'commit to it', and then, 'just do it' without reservations or second thoughts. People that compete that way, don't give up on a hiccup, don't let a hiccup bother them, and just do it again, because they believe it is their destiny. They will their way to win. Once any chink in that armor appears, and they in the most recessed way doubt it is their destiny, they miss the putt, the ball, the kick, the catch or throw, etc.
In Tiger's case, can the reasons for the swing changes, including changes in response to the knee injury, long term body endurance or wear-out considerations, lead to the piling up of doubts, where the belief in destiny is replaced with work to change things because of doubts?