“Difficult to see. Always in motion is the future..” – Yoda
We don't know what tomorrow will be like. A calendar or a schedule and experience can give us some idea but we never know for sure what tomorrow holds.
We can, however, do things ahead of time to better the chances that tomorrow will be a good day.
I know people that make sure they can do the things that make them happy. Routines work! For example, I know people that go to the gym daily; it brings them satisfaction that they can count on. I know people that buy the morning newspaper from the same news-seller and I think the dialog between them is more important than the newspaper.
Once you can identify things in your life that make a day good, you can put them into your routine and know that there will be at least SOME good.
You can also have "good-day-makers" at the ready. I own three clown noses. One is at my office, one is at my house, and one is in my car. Whenever I need a boost or I see someone that might need a smile . . I put on a nose. The day is bettered.
I also keep stamped postcards at my office and sometimes I send them to random friends. They might be long-held friendships or new. Real, physical mail makes a day better; both in the sending and in the receiving. Maybe your thing is a special snack: you should have those available when and where you need them. If you have a sibling or friend that always makes you laugh, remember to call them when you need to.
You can also do traditional planning. Knowing what you want to accomplish and how you are going to do it can make a day good by reducing all sorts of stress. Life is easier when you don't have to rush or have too many things to do. This sort of planning isn't for everyone but there are tools to make it easier. Find the one that works for you and use it.
Preparing today can make tomorrow more likely to be a good day (and it can do good things for today too!).
