Usually I do not ask for help, but try not to overdo the back. Answer, find a way to use leverage, lifts, or simply an easier way to do whatever. As in sheets of plywood, big back destroyers.
A bit of exercise is good, an overdone exercise program is bad. Leads to trouble.
At 86 in 2 months have been fortunate in the health issues. Always worked hard but tried to be smart about it, ala Lazyman.