John 15:16
16 Ye have not chosen me, but I have chosen you, and ordained you, that ye should go and bring forth fruit, and that your fruit should remain: that whatsoever ye shall ask of the Father in my name, he may give it you.
We did not choose God. He chose us. God decided to call us to him and give us his love. He chose to send his son to die for our sins. He chose to forgive our sins. God chose to give us the calling that he had for us. So, when you think that you chose to become a sunday school teacher, choir leader, or preacher, because you love it so much, you are wrong. God put that desire in your heart for that calling. He chose that calling for you before he ever pulled at your heart to come to him.