Tomorrow will be a better day. 

It reminds me of the line from Gone with the Wind – “I can’t think about that right now. If I do, I’ll go crazy. I’ll think about that tomorrow.” When Scarlett said it, she meant that she would not dwell on the negatives and the challenges she was facing.  She’d put them off and consider them at another time and just focus on she needed to do in the present.
Some people are just born with an optimistic outlook.  My Mother always claimed she was a “Pollyanna”.  “This unconscious bias towards the positive is often described as the Pollyanna principle. The concept as described by Matlin and Stang in 1978 used the archetype of Pollyanna, a young girl with infectious optimism.” It’s funny – I never saw her that way.  Maybe it was because she was so quiet – even around us who knew her and loved her the best – she was not real loud and boisterous. That wasn’t her.  She was just quiet.
I’ve never thought of myself as positive or optimistic.  I (like my Dad was) am a pessimist.  My Dad was a worrier, and he lost his patience easily. If there was something to fret over, he’d do it.  On family vacations, my Mom would pick a destination and have a pretty good idea where we were going.  He’d get nervous if we didn’t get there in five minutes, and the trip seemed long or overly adventurous.  We got so used to him saying, “Where are we going?  We’re going to drive, drive, drive and never get there.”  He was not a good traveler.  I get that from him, too.

Espero que tengas un buen día. (Spanish – I hope you have a good day).

Bonne journée. (French – Have a nice day).

Buona giornata! (Italian – Have a good day!)

I never let my sons leave the house without saying, “Have a good day.  I love you.”  Although I, too, am not usually optimistic (I am more of a pessimist and a worrier), I figure it doesn’t hurt to start everyone off with a smile and a verbal hug. It can’t hurt.
I am a believer in turning things around when you do have a bad day.  If you resolve within yourself that tomorrow will be better and face the day with fresh enthusiasm, it usually will turn out to be true.  I believe that life (like anything else) is what you make of it, and there’s not a lot you can do about some things.  If you expect bad, you usually get bad. If you look for good, you will get good.  Wow.  Maybe I have some “Pollyanna” in me after all!