God has not asked for any part of our life. He has demanded all of it! It has been said that we must not grow tired of doing the works of God, but how can we grow tired of doing something that we do not do? We all have our 'legitimate' excuses for avoiding our obligation and these may very well be our stumbling blocks. It is the servant that is found working when the master returns that is blessed. Remember, the body is made up of various parts, which are not interchangeable; but each serves a specific purpose for the whole. However, there is no part that does nothing.
The thing that we have is a desire to be like God. No matter what job we do, without that desire, there is no growth. We must want to grow and we grow by doing. Try a test: take a scrub brush and scrub the palm of your hand and then the inside of your forearm. Note that it is the hand that can take the punishment because it is accustomed to hard treatment. It is tougher, more durable, stronger, and not as easily hurt. Salvation does not come by works, but growth does. Why bother to grow if you are never going to use it.