Way back in 1990, I was young, fresh out high school and looking for a job doing anything I could to make a buck.  I found lots of work, but not a lot of bucks.  It was late June or early July I think.  I was helping build a fence.  And we were digging post holes the old fashioned way, by hand.  I'd been digging holes since sunrise and not really paying much attention to the clock, cause I was getting paid by the hole!  Needless to say, I took few breaks for water and I paid for it.  Around 2 or 3 in the afternoon, we finished up.  I realized I wasn't sweating so much anymore.  I didn't know it at that moment, but that was very, very bad.  A few hours, a trip to the ER and couple of IV fluids later, I found out that I came dangerously close to full on heat stroke.  It over takes you quickly and trust me, if you've never been in this situation, it's painful.  I spent days recovering and lost out on some good money!  It was tough lessen for a young guy, but one I won't ever forget.  When you're out in this heat, take frequent breaks, drink plenty of water and start and finish as early as possible.  You'll be glad you did!