In the summer I work 6 hour shifts in the parking lot watering plants from 12-6. It's so dang hot out there. Sometimes cresting above 100* plus the hot asphalt. I always do my workouts in the morning. It gives me a reason to get up and go. If I woke up just to go to work I'd probably be pissed all the time. I'm also convinced the air at 5 AM tastes better. Much more crisp with a cool chill (even when the daily temperatures push the upper 90s). Being the only one on the roads is nice.

The first few weeks, my workouts suffer, but before long I'm adapted. Just eat healthy and drink plenty of water. Rest is very important as well.