I guess I'm one of those people that likes to understand the how and why of everything I do. Therefore, whenever I workout, I find myself wondering about the purpose of each particular exercise. Am I actually working, strengthen, or stretching my muscles in a way that is beneficial to my body or am I just wasting my time? Am I doing the exercises correctly or am I setting myself up for an injury? Perhaps that's why I love the Anatomy series from Human Kinetics. They have a number of different books that take a deeper look at Stretch Training, Stretching, and Yoga exercises.
Yoga Anatomy has full coloured pictures of the body for a wide variety of movements: breathing, standing poses, sitting poses, kneeling poses, supine poses, prone poses, and arm support poses. These pictures show which muscles are in use during a particular motion. Extra information is then included about which joints are involved and which muscles are lengthening and working during the process. Each entry also notes proper breathing as well as information on any challenges associated with the pose.
In this way, there is no guess work involved. I know exactly what each posture is meant to do, which muscles I'll be working, and how to prevent injuries. I can then take full responsibility for my health and fitness.