Please Pray For Me!....

Prayer is one subject that I really struggle with. Day after day I am surrounded by people who believe in it's power. But do they really understand how it works? When we ask people to pray for us...does this imply that God is swayed one way or the other depending on how many people call in? Doesn't this undermine the notion that God will answer each individual prayer, and that the outcome is predetermined? If so, then why do I need a multitude of other people to pray the same prayer? To me, this seems to imply a lack of faith on the behalf of the person asking for God's consideration. In fact, if our lives are predetermined, with the exception of free will (which is another enigma that I won't even touch on right now)...why pray at all? God doesn't change his mind, right? So if I get cancer, and God's plan is for me to die from cancer...who am I to ask God to heal me? Some will argue that we are not to pray for healing, but rather to pray that God's will be done in our lives. Does God need to be reminded of this? Isn't that kind of the idea? Why pray to God to do something that he's already going to do anyway? This is mind boggling...

If there are any Christians out there reading this...can you explain how or why prayer works? I feel like my brain is going to overheat and explode.