On a side note, I've never been very great with very bad days in the summer. I always tried to keep up with my dad when I worked with him in the brick yard, but I can still remember nearly passing out working box-cars on some summer days. I literally lost time I was so out of it, stacking bricks as cubes he pulled out fell apart from poor install.
I always hated [censored]-week during football, too, though I forced myself to muscle through it and usually was more of a leader than a follower during the obstacle courses.
At the academy I gave up. There were so many in-shape guys that I had no choice but to fall into the middle of the pack and even there I suffered as I tried my best not to be overcome by the heat.
Just last summer I almost blacked-out while after 2.5 hrs of mowing my lawn without a break (yeah, dumb!) I literally barely made it into my basement, stripped down to my skivvies and lay down on the cool tile floor before passing out for an hour. I woke up with a headache and dragged myself upstairs to chug a ton of water, then lay down next to a fan for a bit longer still before I felt OK.
That was the day I decided to get rid of my 19" mower and buy a 28", dual-blade mower to cut my mowing time down substantially.
Cliff notes: I hate heat!