along in years
Advanced in age; old or becoming old. I might be a little bit along in years, but I'm no fool when it comes to technology! Your grandfather's along in years, so you may need to speak a bit more loudly around him.
along in years
Also, on in years. Elderly, old. For example, Grandma's along in years now and doesn't hear too well, or Our dog is not as frisky now that he's getting on in years. This idiom transfers the length of along (and the "onward" of on) to the passage of time. [Late 1800s]