“So do not worry about tomorrow; for tomorrow will care for itself. Each day has enough trouble of its own."
In the previous verses of Matthew 6, Jesus has been teaching on trusting God with our lives and looking to Him for provision, instead of worrying. Now He ends His dissertation with a most pragmatic statement: Don't borrow trouble. Don't spend today thinking about what's going to go wrong tomorrow. God gives enough grace for each day. His grace is sufficient for today, and His grace will be sufficient for tomorrow. Each day has the potential to bring something for us to worry about. But don't lose the exquisite experience of life with God today, by fretting over what might be coming tomorrow.