I don't believe you have to run a marathon in training to race a marathon but you need to know what you have to do to get ready.
I wasn't ready my first trip and those lessons got me through the trail a lot more comfortably the second time.
There are a lot of things people can do to make this trip a lot easier on themselves.
If you are a SoCal or NoCal day hiker there is no excuse for not going to 14,000' before your Whitney trip, if your hike is in July or later. White Mtn. is there for the taking in late May or early June most years. This is a better test than anything you will find in SoCal or NoCal.
Then there is the headlight thingy, most will not go out to the favorite trail in the dark to see their light is worth the money they paid for it.
BTW, I've seen a tri-athlete blow out his energy stores by the sheep pens at Barcroft Labs, White Mountain. He had one heck of a bad day this easy fourteener.
