Sit in meditation, but do not think. Look only at your mind. You will see thoughts coming into it. Before they can enter, throw these away from your mind until your mind is capable of entire silence.
I think that those who serve most potently, work on levels of consciousness that have to do with radiating love — maybe God's love... It is important that you have a brain and use it, but that is secondary. The basic premise is that you allow something to come through you. Then you use your intelligence to give your heart's work discipline and logic. But the transformative energy, that which can change events, that heals, that helps, that serves, comes from somewhere deep inside.