I am now 66 and plan to sail from Norway to the Caribbeans this summer, as I just retired last month. Maintaining the machine seems to be a rejuvenating process, as the space is really small and I must work in all kinds of positions.
Since i live in the ship I no longer have a car, thus I walk to any destinations. In the summertime my ship is moored an I must row the dinghy ashore. Walking and rowing is indeed very good for the health.
The only investments I have made in order to be prepared for later times is a windlass with both a cabelar for chain and for rope. In case I some time in the future will need it haul the mainsail. Anyway I use it now to haul my son to the top of the mast to do the maintenance there.
Use your head, ram the wall till it falls.