I keep a gratitude journal. Every evening, I write about something from the day that I’m grateful for. I try to write in detail, filling about half a page. It helps.
I actually have a huge problem with this. I struggle with depression and am married to a narcissist. However, I have always been able to understand that things always have room to get better. It doesn't matter what it is, there might be another better level of it. And the odd thing is that despite at times drowning in depression, I've always been an optimistic person. I guess that is where my gratitude lies. In the ability to see the good in things.