At my age, soon to be 68 (already 68 if you count conception), things go wrong. I have trouble with back, knees, feet, etc. I'm happily surprised on any day everything works right all at once.
One thing that helps me put up with all that is to simply remind myself that no matter how much I hurt, Jesus hurt worse. The Morning Offering is especially helpful here too.
Speaking of which, the Morning Offering is one of my regular prayers. Also Hail Holy Queen, the Prayer to St. Michael, and the Memorare. Also meatless Fridays. It's just easier for me to go back to the practices of my childhood. Keeps life simple.
Trouble is that a tuna sub from Subway, or a veggie pizza from my favorite joint, isn't really a penance!
The Way of the Cross according to St. Alphonsus Liguori has become my favorite devotion. I'm trying to memorize it so I can pray myself to sleep with it. I can't imagine it doing any harm at all to meditate on the sufferings of Jesus. We were purchased at a great price, says St. Paul. (I think St. Paul.)