^^^ ok, Richard, here's the long short story... :O)
Have had some pretty good periods healthwise allowing much activity. Learned quite some tricks on how to lift, how to carry, what positions to avoid, when to pause etc etc, and to be wary of overethusiasm \ overestimation of abilities > stop and throw in the towel and call in someone to help.
Constant evaluation and planning. Took years, but now previously 'backbreaking' work actually can be strenghtening (of the support musculature). Sitting is actually backbreaking for my condition, very troublesome, this combined with the vertical compression jolts and shocks from sitting on a bike seat strongly affects any eventual motorcycling plans. Sold 3 bikes, + 2 cars whose seats wrecked my back. A10 kept, but in a sad state, still in pieces (but one day...maybe).
About the demolition hammer, of course seemed like machinery designed to demolish anyones health :O) and put them in hospital or worse quickly, but felt a strong urge to try to push some limits, not accepting any (automatic) preconceivement about not being able to do this or that. Quickly learned how to minimize back impact. Hammer mostly in an as much as possible vertical position makes it very manageable, any controlling then provided by muscles in the arms, the back will more or less just do a balancing job. Most heavy part is actually carrying it to the area of activity.
Time changes everything, things can go wrong quickly (again), or may continue doing positve stuff for a good while, no idea, just need those fine days of activity and creativity (...along with some doses of morphine a few days pr. month, good stuff when used properly) to keep the spirit alive and well.
Anyway. The demolition hammer did a superb job in the field ...and in the operator :O) Did definitely not kill me, on the contrary, strenghtened arms, legs and back, and induced a very welcome portion of confidence in myself, unveiled abilities.