Kelly's book explains the origins of his ambition to become an astronaut, reading Tom Wolfe's book The Right Stuff, and the many trials he overcame to be one. Endurance describes the physical and emotional stresses, loneliness, tedium, and painstaking routines and risks astronauts face during months in space. Kelly also describes the unparalleled awe and wonder of being in space, especially the experience of viewing Earth from above while orbiting the planet every 90 minutes at an altitude of 250 miles and at 17,500 miles per hour.
"It's hard to describe the experience of looking down at the planet. I feel as though I know the earth in an intimate way that most people don't – the coastline, terrain, mountains, and rivers. One of my favorite views of Earth is of the Bahamas – a large archipelago with a stunning contrast of light to dark colors. The vibrant deep blue of the ocean mixes with a much brighter turquoise, swirled with something almost like gold, where the Sun bounces off the sandy shallows and reefs. Whenever new crewmates come up to the station for the first time, I make it a point to take them to the Cupola (a module made entirely of windows looking down on Earth) to see the Bahamas."
This NASA video captures the full 90-minute experience.