I can't recall where I first heard the idea for a Good Things Jar - it may have been Reddit - but the concept is a simple one. Every time something good happens to you, write it down on a strip of paper and keep it in a jar. On bad days, or simply when you feel low, take out all the paper strips and read them.
My Good Things Jar is a Word document, ordered by date. It's mostly little events like successfully preparing a new dish, or meeting up with friends, or having an exceptionally productive day, or reading a thought-provoking essay, or simply viewing a nice sunset. All the little things that make me happy. And when I read about them again, weeks later, it's like reliving those happy moments again. It reminds me of how many good things happen every day.
I think I need that reminder, sometimes. That I am living a good life. That nice things are happening to me, all the time. That I have the right to be happy with what I have.