I don't have a problem with being 50. I accept that I'm not as young as I was; that I've got gray in my hair; that things have relocated themselves further south than when I last inspected them; that I have the ambitions of a 20 year old and the knees of a 50 year old; and that as I age, the little things matter less and less.
That's the really good part. :) When I turned 30, it was like magic - the problems that had obsessed me all through my 20s just drained away, leaving me to wonder what I'd been so worked up about. My 30s were about enjoying my lack of 20-something worries.
50 looks promising. We just passed our third wedding anniversary, my tolerable job (which grew intolerable) is gone and my hobby is now a fledgling business that I love. My house is thus far surviving the Polar Vortex that has enveloped the Northeast and the heating bill has been only enough to make me dizzy, as opposed to get sick on my shoes. I've discovered new things I like to do and more places I'd like to go.