I usually sleep with the AC set at 75º -- during the day it'll be anywhere from 76-85º (when it's nap time). One night I forgot to set the thermostat for sleeping and I could feel the discomfort. I woke up sweating through the sheets. I got up and checked the temperature.
76º.
I read the book called 212 several years ago. It's a really short book whose entire message was about the temperature of really hot water versus the temperature of boiling water. At 211º it's really hot; at 212º it's boiling. The water was used as a metaphor for the reader's effort, belief, confidence, energy, etc.

One degree can make all the difference. Thing is, you never know how far -- or how close -- you actually are to that one degree.