In the past 10 years, yoga has become wildly popular as a workout. Unlike typical gym activities, such as running on a treadmill and lifting weights, yoga is an age-old form of exercise that incorporates strengthening, breath work, stretching, and balance — it's a combination of physical, mental, and spiritual traditions. You may not think that lying on a mat or holding certain poses will give you a full-body workout, but yoga is definitely more than stretching. A total-body workout includes aerobic exercise, training for muscle strength and endurance, and flexibility exercise. While the cornerstone of yoga practice is flexibility, when you hold a stretch for two minutes or more, you work your muscles in a way you wouldn't during regular strength training sessions. Yoga also involves becoming aware of your body — what you eat, how you eat, the nature of your other fitness activities, and how all of these affect your body. Although yoga has many benefits, it's not a substitute for other forms of exercise, especially once you get good at it and it doesn't present you with as much of a challenge. So be sure to do your cardio and weight training on other days of the week, even if you unwind a couple of days with yoga!