Have an Answer?
That is a very noble calling! I recommend you look into talking to pastoral counselors and getting their perspectives on religious counseling. Serving as a missionary might also give you a good start.
One thing I would caution you against is to get your mind set on "huge differences" right away. You need A LOT of experience before you can deliver such impact. You also never know the true extent of your help on someone's life. What may seem trivial to you, may mean the world to them, and so is immensely valuable.
Join a church that believes what you believe and then let God guide you from there.