In high school, my gym teacher started most cold days out with this statement. Usually we were outside running. I had first hour gym, so it was usually around 8 in the morning.
Throughout my life, I always try to remember this on particularily grey, cloudy, cold and snowy days.
I found out later this gem was from Frank Zappa - but I will probably continue to think of it as his own unique wisdom/perspective on life. Thanks Coach K.