Jesus told us to live in the now moment.... To face each day, only.
Paul teaches that we are to put on God's Armor each day, and stand.
So, what can happen, is that the Christian or the unbelieving person, can add = yesterday's heavy regrets...... and anxious concern about what will happen tomorrow.
So, now you have put yourself under a TRIPLE LOAD, under much more burden that we are designed to carry, and when you try to carry all that, .. given time, you will break down.
Saint, reader... yesterday is gone, and tomorrow is not promised to us, so, we must live only in Today. casting all our care(s) upon Jesus who is our strength.
The NT tells the Believer to "be careful for nothing".....(Don't Worry)........>"but in all things, in all situations, give Thanks".
Paul said that life situations that come and go, are often very perplexing, but, we are not to be distressed, as "all things things will work out for our good".