Meaningless living

Every saturday, my dad would bring my grandparents over to our place to spend a day away from their own home - an old 2 room hdb flat, where they are taken care of by my parents (sometimes i have to give a share of effort too) instead of a paid neighbour during the rest of the week. My mom would cook them proper meals for lunch and dinner; an old folks diet that i would have to eat too.

My grandmother is senile and cant even remember who i am. my grandfather is still mentally sound but physically he looks like he could breakdown anytime. When they come to my place, they spend the day doing nothing but eat, sleep, and watch TV - which i dont think they even absorb anything from it.

I could imagine how they spend the rest of their time at home.
Wake up, stare into space, watch some TV, eat breakfast and lunch, take a nap, watch more TV, eat again, stare blankly again, then go back to sleep.
They cant go out - never on their own. maybe the neighbour would bring them.
they cant hold proper conversations - my grandma would talk about the same things like a faulty tape recorder, and my grandpa hardly talks, even before he became hard of hearing.

The difficult part comes when i try to put myself in their shoes. I so absolutely cannot imagine myself living a life like that... a life totally void of meaning. They just live for the sake of staying alive. Its a fate worse than death.
Its commendable how they can continue living like that without falling into depression. I really dont understand.

I am certain that i would not become like them one day. Seeing their example makes me all the more concerned about preparing for my twilight years - even though those days are too far to even consider. Ill make sure i have active ageing, and even in my final years, to contribute to society in one way or another, being a blessing to people around me. Lest i live a life worse than no life at all.