Matthew 6:26-27

If we fret constantly about having enough food and clothing, we show that we have not yet learned a very basic lesson that nature teaches us: God provides for His creatures’ needs. Furthermore God is the heavenly Father of believers. Consequently He will take special care of them. This argument is a minori ad maius, "From the lesser to the greater." This does not mean we can disregard work, but it does mean we should disregard worry.

Fretting cannot lengthen life any more than it can put food on the table or clothes on the back (Matthew 6:27). Worry really shortens life.