It is disturbing how many Christians give lip service to prayer, but do not really trust that their prayers are answered. A missionary once received a letter from a little girl whose Sunday School class had been writing to foreign missionaries. We are not expecting an answer. Without realizing it, that little girl summed up the prayer life of many Christians. The truth is, most of us aren't surprised when our prayers are not answered- we're surprised when they are.
Prayer is a powerful weapon.
When we pray for and with other people, we create a community of faith. This is why Paul wanted people to pray for him while he was in prison. It was a comfort for him. He knew that the community of faith stood behind him in his hardships as well as his victories. And he received strength.