There has been much written about this subject and what it does to the body, let me pass on a personal experience on a subject i know all about or thought i did from past experience.
This past week, I was fishing Pa"s limestoners, caught some hefty fish, ,temp was in the 40's in waist deep water, we fished all day in a steady drizzle, but the sight of wild trout was too much, keep fishing, towards evening,as we were exiting the stream walking was difficult.the first sign. My partner and i split up and he headed home. I headed for coffee. Not being able to get the right change out of my hand at the coffee shop . sign#2. A 60 mile drive and 2 more coffee stops. no problem,I can make it home. I am an iron man or so i thought, former marine, marathon runner and all that crap.Tough guy.

With the stereo turned up, 3 large coffees in me, I was awakened by the sound of tearing metal , the unmistakeable smell of gunpowder from the airbag charge going off and the steering wheel being wrench out of my hands as i hit a bridge over a creek so close to home. thankfully no one was in the other lane or behind me. Fell asleep at the wheel. Next time when i feel the fingers of cold creeping in i have good reminder of torn metal and broken glass to think back on. Don't let this happen to you. There is always another day if you use you head.