A stressed mind = stressed muscles = negative, anxious thoughts. 

A calm mind = relaxed muscles = positive and uplifting thought patterns. 

Physical and emotional tension is inextricably linked. The word Yoga means Union. When we practise Yoga, or mindful movement and breath awareness, we begin to understand that the two are not separate entities at all. Each one has an effect on the other. When the physical tension in our body is released, we create space and an allowing for the mental tension to release. When our mental tension is released, our physical tension begins to dissipate, 

The physiological stress response means an increase in heart rate, muscle tension and elevation of cortisol and other stress hormones. Yoga and meditation help to trigger the relaxation response in our bodies, decreasing stress, depression and anxiety and increasing our overall happiness.