"It is written," He said to them, "'My house will be called a house of prayer,' but you are making it 'a den of robbers.'" Matthew 21:13. Jesus modeled for us what a house of prayer looks like. Prayer is done out of love for God and not out of need. God openly rewards those who pray from a place of love rather than need.
There is no limit of the power you obtain through prayer. Prayer can override and overwrite what men have said against you. Those who have a prayer life, those who fast, have the power to control situations.