When you come to full draw, your upper body should be as square as you can get it to the target.........if your torso remains upright then you are only dropping your arm.
You need to get your upper body in as close of a position as you can to what you would be shooting if you were level.
Don' t just stand straight up and down and lower your arm and sight to the target.

Sometimes a simple fear of heights will prevent a hunter from bending at the waist becasue it takes your body out closer or over the edge of your stand' s platform.