I had a similar thing happen to me, but still in highschool, where I pulled allnighters to make an insanely stringent schedule work so I could catch up to those pesky A+sians that played the Violin and helped blind orphans speak (or something along those lines).

I mean workwise, I feel better sprinting short burst than to walk for long periods, but trying to take on a 4 year death marathon, starting at 6 in the morning and ending 2 in the evening, wasn't much of a bright idea. I ended up crashing every second term, to get sick weekly during that time and to pull down my hard earned grades into the D range.

I believe that the mind is a lot like muscle in that respect. Don't excercise it, and it will atrophy. Strain it constantly, and it will break down, along with your bodily health. The point to building mental muscle seems to be alternating between periods of excertion and recuperation. Anyone telling you that carrying weights constantly is the path to strenght is proably trying to get you to build their pyramids, pulling stone slabs up an incline day and night.

Just saw your very eloquent reply to my comment. Great analogy.