I like your way of thinking. I work in the insurance industry, Primarily life insurance and I come across this quite a bit. Donating your organs can be done very easily and often governments will have a register you can sign up to. However in regards to leaving other major body parts, like hands for example can be a lot tricker yo u often needs to be at tip top health. People have the same issue when donating their bodies to science.

Take care of yourself, not just so you can donate, but so you can live a full fun life too!