"Enjoy the little things, for one day you may look back and realize they were the big things."The only thing I'd change here - as if I could ever change someone else's quote, but humor me for a moment - is the "may" part.
Indeed, little things are big things, but most of us seem too preoccupied to pick up on that subtle cue. When you run out of "things" - or, to be more precise, time - you quickly realize the smallest moments are, in the end, the only things that matter.
Your turn: What's the most important little thing that's happened to you - lately or ever?