Our body is a machine for living. It is organized for that it is its nature. Let life go on in it unhindered and let it defend itself.
If in preaching the gospel you substitute your knowledge of the way of salvation for confidence in the power of the gospel you hinder people from getting to reality.
If you tell God no because He won't explain the reason He wants you to do something you are actually hindering His blessing. But when you say yes to Him all of heaven opens to pour out His goodness and reward your obedience. What matters more than material blessings are the things He is teaching us in our spirit.
It's a funny thing because you look at the careers of other filmmakers and you see them sort of slow down and you realize maybe this becomes harder to do as you get older. That's sort of a cautionary thing. I hope it doesn't happen to me.