What is the power of prayer?

This morning I awoke with a heavy heart about our nation.After writing to my pastor I find myself praying for revival in America.In Mark 9:18 Jesus confronts a demon controlled man and the people there had asked the disciples to cast it out,but they were unable to.Jesus has given us the power to do this but He also tells us why we don't see it coming into fruition.We lack the power of prayer,listen it is through the power of prayer that our faith really begins to take effect.If we want power to touch the world,our nation and peoples lives for Christ we must spend time with the source of that power Jesus Christ through prayer.