It may sound kliché but I mean really make an effort to avoid the thoughts. Think of at least five things that was great with the day, then think of five great things that will happen. It isn’t so important if the things you’re thinking about are tiny like “I took a walk today” or big things like “I got good grades on the test”.
Don’t make things bigger than they are
If you have a problem and you’re very worried about it, it’s good to talk with someone else about it so they give you their point of view instead.
Search for “mindfulness” on spotify and just listen to it until you fall asleep. My opinion is that I relax when I hear the sound of the nature or the sound of the waves and the sea.