If we can change from that deeper place - for instance, if I am constantly going around telling myself and everybody that I'm a failure and I'm worthless, that's a reflection of the thoughts I'm having. The moment that I'm able to shift at the level of my mind and start seeing that I have something to offer, life is important, and I want to contribute, then that tiny subtle shift from the inside can have a profound affect on my external life.
I don't pray for anything, but I have used affirmations in the past a few times. They are really a bit more like realizations in that on some level they have already happened.