not as young as (one) used to be

not as young as (one) used to be

No longer as physically fit or able as one might have been in one's youth. You shouldn't try to tackle such demanding hikes—you're not as young as you used to be. I think it's time I started cutting down on my drinking. I'm not as young as I used to be, after all.
See also: not, used, young
Farlex Dictionary of Idioms.

not as young as one used to be

Fig. getting old. Aunt Lila isn't as young as she used to be. She can't take a lot of trips anymore. Don't walk so fast! I'm not as young as I used to be. It takes me awhile to catch up.
See also: not, one, used, young
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • not as young as one used to be
  • back-breaking
  • grapple
  • grappling
  • (as) strong as a horse
  • (as) strong as a lion
  • frustration
  • throw (one's) arms up in despair
  • throw (one's) arms up in frustration
  • throw (one's) hands up in despair