Yesterday I got a reminder from Mars! There is a ‘Starmus’ conference going on these days, in Trondheim, Norway. One astronaut told about returning to Earth after 43 days in Space - the message being that what you don’t use (in Space) you have lost when back (on Earth) - i.e. without gravity your sense of balance get lost - you have to retrain basic mobility capabilities upon return.
So also for elderly people - without exercising mind and body capabilities get lost. Thats why daily dogwalking keeps me (and the dogs) going.
Beware also the mental vulnurality. Who recalls phone numbers these days? Say your phone got missed and you need to ask someone else to make a call for you - would you be able to tell the number to dial?