Do not think of yesterday, for it has already passed and will never return. Do not think of tomorrow either, for you do not know what tomorrow will bring. You must therefore think only of today, and you will then sense the all encompassing delight that this day has to offer.
Even though you are now in the midst of great difficulties, and it seems to you that this day is full of pain, problems, vexations and constrictions, you must nevertheless truly contemplate your situation. You will then see and realize that all the confusion, all the bitterness and agitation you feel today, is due to the fact that you still bear the burden of the previous day, or that you are worried about the coming day.
Adapted from Only Today: Based on the Teachings of Rabbi Nachman of Breslov and of His Student Rabbi Nossan of Breslov, by Mohorosh HaKodesh Breslov