From someone who knows:

Quite apart from the danger of the combat environment, it’s hard to conceive of the purely physical strain they are under. Imagine patrolling on foot day in and day out in temperatures 10 degrees hotter than NYC today, wearing and carrying between 40 and 70 pounds of armor and weapons, for 6 hours (on a good day) to 10 hours (on a standard day.)
God bless them, indeed.