here are some thoughts / suggestions....
physical fitness is more important than many realize. so the number one concern should be staying fit and flexible (strength and cardio), eating right, and getting an annual medical.
we rarely (if ever) hear people discuss any type of warm up before diving. depending on the particular dive site / conditions, getting suited up, carrying gear, the water entry, the dive itself, the exit, carrying gear back, and getting undressed, can add up to quite a physically demanding ordeal.
with every other "sport" or activity, we always see people warming up and stretching etc in order to prep the body and mind for what is coming next.
when is the last time you saw anyone at a dive site doing any of this ?
with aging and declining fitness, there can be a higher risk for cardiac / high blood pressure issues etc. these do not exactly mix well when under water.
as others have suggested above, making changes to your diving style and conditions, along with finding ways to just make things simpler and easier can also go a long way in
preventing injuries and prolonging your enjoyment of the sport.