+1 (+10?) strength (and flexibility) training!
At 61, I have mild arthritis in my neck, hips and lower back and used to come back from long bike rides pretty beaten up (and was loosing interest in cycling as a result). Fast forward after 3 years of strength training (and stretching and rolling after EVERY bike ride): I almost never feel any pain in either hip, back or neck, including after 10kft GFs or somewhat aggressive long MTB rides. It’s been absolutely amazing to me how developing strong musculature protects your joints in addition to making you faster.
I have a pretty robust full body program, but a few elements that may be relevant to your specifically mentioned neck and shoulder issues, include:
- Shoulder shrugs
- Lat pulldowns and shoulder presses (opposing movements)
- Delt fly and Peck fly (opposing movements)
- Lateral dumbbell raises
+1 @batwood14 suggestion re: planks. you can start out at 5x 45secs with 1min RI and increase to 6x 1:30 (as an example of a progression)