"Don't leaf through old pictures when you are feeling down for example"
Made this mistake myself the other day. I really hadn't intended to, but was rifling through a kitchen drawer, looking for documents that I need, and found a whole stack of photos, ranging from right before and right after we'd gotten married, to within the past couple years, including some shots from when we were separated last time.
The pictures from long ago were really tough to see, because I got to see her as she looked when I fell in love with her...astonishingly gorgeous, sweet, and innocent. And, of course, she was hanging all over me all the time. Those hurt a bit. Lucky for me, I'm up to my earbones in crisis management at the moment, so I didn't have much time to dwell on them.