Healing power of prayer is not a prayer. It may be meditation, yoga effect or some psychiatric administered drug creating physiological, psychic or emotional balances. They could recondition body or expand consciousness, but everything directed inside or within one’s self or the body.
Elsewhere in conventional term when one prays, he summons not himself but someone outside the body. Telling what he expects from Him in terms of health, wealth or rain from the sky. Not as instrument of action for the self but for the higher power. Visit a Friday mosque or church and the difference is clear.