How often should I practice hatha yoga (physical yoga)?

1-2 classes per week: Reduced stress, modest improvement in flexibility and balance, modest improvement in breathing,modest postural improvement, better sleep, safe exploration of recent injuries.

3-4 classes per week: All of the above plus significant increase in strength, flexibility and balance, increased energy, better posture, improved circulation and skin, improved breathing, mood, attention, concentration, memory and over all sense of well-being.

5 or more classes per week: All the above plus great endurance and energy, total body awareness and reintegration, profoundly enhanced mental clarity, awareness, emotional stability and sense of well-being