"Not quite life saving, but it sure felt like it at the time:

I didn’t realize I had heat exhaustion and got on a roller coaster. When my vision started going gray at the edges I remembered the Mythbusters Blue Angels episode where they talk about the full-body-muscle-clench thing they have pilots do to counteract the G forces pulling blood away from your brain. I did those clenches for the rest of the ride and managed to avoid passing out, got off the ride and toddled off to a sheltered area to drink some water and cool off.

Lessons about my heat tolerance were learned that day, but the pre-existing lesson about Hook Maneuvers meant I got to learn them while conscious and in private instead of from an impatient EMT after they revived me."