One of the biggest issues I've found as I've aged is loss of strength, dexterity, and even "reach" of my fingers, both right and left hands (NOTE: In my case I've had to deal with some finger and wrist injuries which have exacerbated the symptoms - PB). If you are well into "seniority" (65 or older), haven't suffered serious injury to your hands and fingers, and don't yet have debilitating arthritis, and *IF* you are practicing regularly - and by that I mean EVERY DAY for at least 20-30 minutes, or two-or-more-a-day 15-minute sessions - then chances are good that your fingers stay in fairly good shape for playing. If, however, you are lax in practicing or have been on "hiatus" for a while, you may have found that your fingers have lost some dexterity and strength - and two or three practice sessions no longer puts you back on track like it did when you were, say, 30 years old.
This can be frustrating, and frustration can lead to dissatisfaction with playing at all, which can lead to longer stretches between practices, which can lead to even more decline in ability, etc., etc. In other words, it grows on itself. What to do?
I recently ran across the slideshow shown at the following link when I was researching how to improve dexterity and "stretch" in the right-hand thumb joints, deterioration of which causes me to sometimes "drag" my thumb onto the 4th string when I hit the 5th, especially when playing in the upper registers. Most annoying!
Try these exercises and see if they help you. And if they do, get in there and practice more! Don't let Father Time rob you completely of something you always loved to do!
"When I was younger, I could play banjo really fast. Now I guess you could say my playing is kinda half-fast." - Paul Bock
'Buying Banjo from UK' 34 min
'Mystery Tone Ring' 40 min
'Parson’s Farewell' 1 hr
'1970 Chevy milk van' 3 hrs
'Bacon Belmont banjo' 3 hrs