Don't calculate without God.
God seems to have a delightful way of upsetting the things we have calculated on without taking Him into account. We get into circumstances which were not chosen by God, and suddenly we find we have been calculating without God; He has not entered in as a living factor. The one thing that keeps us from the possibility of worrying is bringing God in as the greatest factor in all our calculations.
In our religion it is customary to put God first, but we are apt to think it is an impertinence to put Him first in the practical issues of our lives. If we imagine we have to put on our Sunday moods before we come near to God, we will never come near Him. We must come as we are.
Don't calculate with the evil in view.
Does God really mean us to take no account of the evil? "Love...taketh no account of the evil." Love is not ignorant of the existence of the evil, but it does not take it in as a calculating factor. Apart from God, we do reckon with evil; we calculate with it in view and work all our reasonings from that standpoint.
Don't calculate with the rainy day in view.
You cannot lay up for a rainy day if you are trusting Jesus Christ. Jesus said - "Let not your heart be troubled." God will not keep your heart from being troubled. It is a command - "Let not..." Haul yourself up an hundred and one time a day in order to do it, until you get into the habit of putting God first and calculating with Him in view.
Lead Pastor @Genesee Road Church of God.