What a difference a day makes?
One day is sunny, the next rainy. Is one better than the other? I don’t think so. They are equal in value until you make use of them. If you squander your time (as I am wont to do), the day is wasted. If you get into a disagreement with someone else, the day will not be a good one.
If you eat a delicious meal, the day is good. If you reach an agreement, your day is made.
So how do you make a day a good one all the time? Delicious meals and agreements don’t occur every day.
Simply don’t let either good events or bad events bother your emotional equilibrium. Keep everything on an even keel.