When we have a good self esteem we love ourselves. Having a low self esteem doesn’t help anyone. God loves us because we are special in His eyes. He thought so much of us that He was willing to suffer in order to help us.
When we love ourselves we should want what is best for ourselves. So what is best for us? Giving up our lives for the sake of the Gospel is what is best. The long term benefits are out of this world.