I worked Monday to Thursday last week. 
8 am. - 5 pm. every day.  Wednesday temps were in middle 30s with high humidity.
Friday I set off about 8.30 am, headed back home about 10 am feeling seriously fatigued.
Since friday night I feel like I've got chest infection/flu type symptoms.  Drunk loads of water, but still feel yeuch!  Don't think I'll be out tomorrow.
Heard of another w/c nearby got heat stroke during the week!  Not funny, Doc says it can be fatal sometimes, take it seriously.  He has to rest up for 3 days and drink salted water every hour.
If you want to be a he-man...good for you,  the graves are full of he-men!