One of the things that can steal our peace is worry about the future. Oftentimes, when we are overcome with worry, we lose perspective. Sometimes, we even lose hope. Over 400 years ago, St. Francis de Sales offered some timeless words of wisdom about worry:
Be at peace. Do not look forward in fear to the changes of life; rather look to them with full hope as they arise. God, whose very own you are, will deliver you from out of them. He has kept you hitherto, and He will lead you safely through all things; and when you cannot stand it, God will bury you in his arms. Do not fear what may happen tomorrow; the same everlasting Father who cares for you today, will take care of you then and everyday. He will either shield you from suffering, or will give you unfailing strength to bear it. Be at peace, and put aside all anxious thoughts and imagination.
When I am really worried about things, I try to remember St. Francis’ soothing words.
Rebecca C. Ruiz 
Wise words indeed. Remember Matthew 6:34 Take therefore no thought for the morrow: for the morrow shall take thought for the things of itself. Sufficient unto the day is the evil thereof.
Thank you, Peter. Yes, very good to remember.