I do not understand someone who will go to all the money and time of making their house handicapped accessible but they won’t spend the same amount of money and time on making their body less likely to become handicapped. Sure, there are accidents that happen but generally the biggest reason that people become disabled is because they stop taking care of themselves.
Being infirm is not a natural part of becoming older. It is a natural result of stopping taking care of yourself. If you don’t use it you will indeed lose it.
Less active means less healthy. Being active shouldn’t be something that just young people do. Being active is something that all people should do. If you stop working when you retire, it doesn’t mean you need to stop moving. Sometimes this means you have to make up reasons to move. Volunteer. Go to the Y. Garden. Stay active, or you’ll become immobile. Take care of your body – it is the only one you get.