It's easy for me to dwell on the negative and spiral into depression, so I have to actively focus on the good/positive things I experience to rewire my brain. Whenever something nice is happening (it can be as simple as liking the homemade matcha I made), I note it in my mind (something like "this is a good thing happening to me") to remind myself in the present that good things happen to me. And with that same example, I can add on the bonus thought that I made that good thing happen.