I don't consider myself an experienced hiker at all, more of a newbie than anything. The longest hike I've ever done was last weekend (Seven Pines Trail to SJ Peak), the longest run I've ever done was a half marathon.
I'm in pretty good shape, but definitely could be in better. I've got a couple things working against me: I don't have a lean body type, and I have a connective tissue disorder that causes hip joint pain and injuries on a regular basis.
It might work for other people to prepare less, but I know for me personally I need to be very prepared based on these factors.
BTW, I think that age is not much of a factor when comparing between different people. Three of the guys in my Whitney group are all significantly older than me and in much better shape than me. I know they will kick my butt up that mountain. :whistle:
