Mind, Body, Spirit means that our well-being comes from not just our physical health, but also from Mental health and Spiritual health as well. Your mind is affected by your body, and vice versa. Similarly, mind is affected by your spirit, and vice versa. E.g. If the body is in pain, mind is not at ease. Sleep is affected and further health problems arise. This is no inner peace. Yoga brings all into harmony!
"Yoga for Everyone" Datta Kriya Yogo Vivardhatam!!