[T]omorrow is a new day. You shall begin it well & serenely, & with too high a spirit to be cumbered with your old nonsense. This day ... is too dear with its hopes & invitations to waste a moment on the rotten yesterdays.
Take all reasonable advantage of that which the present may offer you. It is the only time which is ours. Yesterday is buried forever, and to-morrow we may never see.
But our minds are bound to the yardstick of yesterday, today and tomorrow, and with that yardstick we try to inquire into the unknown, to measure that which is not measurable.
What we are today comes from our thoughts of yesterday, and our present thoughts build our life of tomorrow: our life is the creation of our mind. If a man speaks or acts with an impure mind, suffering will follow him as the wheel of the cart follows the beast that draws the cart. If a man speaks or acts with a pure mind, joy follows him as his own shadow.
It is not enough to want to make the effort and to say we'll make the effort. We must actually make the effort. It's in the doing, not just the thinking, that we accomplish our goals. If we constantly put our goals off, we will never see them fulfilled. Someone put it this way: Live only for tomorrow, and you will have a lot of empty yesterdays today.
I never felt so fervently thankful, so soothed, so tranquil, so filled with the blessed peace, as I did yesterday when I learned that Michael Angelo was dead.
For you [God] are infinite and never change. In you "today" never comes to an end: and yet our "today" does come to an end in you, because time, as well as everything else, exists in you. If it did not, it would have no means of passing. And since your years never come to an end, for you they are simply "today."
So yesterday you fell off the wagon? Or maybe you blew your diet? Or lost your temper and shot off your mouth? Well, that was yesterday. Today is a brand-new day with a clean slate, so forget yesterday!