The term "yoga" comes from a Sanskrit word meaning "union." Yoga combines physical exercises, mental meditation, and breathing techniques to strengthen the muscles, relieve stress, provide cardiovascular conditioning, and increase Mind/body awareness which can influence mood and self-esteem to improve quality of life. The yoga philosophy maintains that the breath is the most important facet of health, as the breath is the largest source of "prana," or life force, and hatha yoga uses "pranayama," which literally means the science or control of breathing.
A typical hatha yoga routine consists of a sequence of physical poses, called asanas, and the sequence is designed to work all parts of the body, with particular emphasis on making the spine supple and increasing circulation. Each asana is named for a common thing it resembles, like the sun salutation, cobra, locust, plough, bow, eagle, tree, and the head to knee pose, to name a few. Each pose has steps for entering and exiting it, and each posture requires proper form and alignment. A pose is held for some time, depending on its level of difficulty and one's strength and stamina, and the instructor cues participants when to inhale and exhale at certain points in each posture, as breathing properly is a fundamental aspect of yoga postures. Breathing should be deep and through the nose. Mental concentration in each position is also very important, which improves awareness, poise, and posture. During a yoga routine there is often a position in which to perform meditation, called dyana, if deep relaxation is one of the goals of the sequence.