Prayer can have a positive benefit. I had an incredibly severe health problem about a decade ago and the doctors didn’t give me one chance in hell of living. My mother started a prayer vigil in my home home town the night that I went into ICU. It wasn’t anything supernatural. I just knew that lots of people cared I couldn’t let them down. I recovered fully against all expectations because I was determined to. Mental state versus health is a very real phenomenon and prayers are one very good way of expressing that.