Be yourself is a phrase which implies stagnation.
I heard a joke once that "past me was an ass hole, and ate that cake so now I've got to run." or something like that. That's the way I try to think about this. If I don't look back at past me with a little bit of that same feeling I get when looking at old code then I haven't grown. And I try to use that to remind current me that future me matters too.