Images Credits: fig. chapter opening | Photo by trail on Unsplash; fig. exercise | Photo by massimiliano morosinotto on Unsplash; fig. 1 | Photo by Dan Petty on Unsplash; fig. 2 | Photo by trail on Unsplash; fig. 3 | Photo by Matheo JBT on Unsplash; fig. 4 | Photo by Patrick Ryan on Unsplash; fig. 5 | Photo by Cristian Palmer on Unsplash; fig. 6 | Photo by LI FEI on Unsplash; fig. 7 | Photo by Joseph Barrientos on Unsplash; fig. 8 | Photo by Adam Jang on Unsplash.
