Sentimental Second Thoughts

I'm not a very sentimental person.  This was something I decided decades ago.  As a child I worried that if I really cared about something (a toy, an award, etc.) then what would I do if it were taken away or lost?  I figured if I didn't care about anything, then I couldn't get hurt.  For the most part this served me well.  However, I'm finding that when I look back on experiences, memories, photos... well, something seems to be missing.  Not sure what, but something.  Perhaps this is some crazy holiday induced worry, "I've not a tradition or keepsake in sight?!"  Maybe this thinking is something that comes with getting older.  Or maybe it's a side-effect of living in a consumerism society littered with Hallmark holidays.  Whatever it is, I've no idea what to do about it, if anything.