When cells that are supposed to fight disease in our body gets weak, definitely old age has begun. Sometimes sickness causes our cells to be weak and dead.
You don't need to be afraid about old age. You only need to start now and prepare for it, knowing that it will come and with challenges.
Living your best life with people matters a lot. At old age, you will need this same people to help you when your muscles are weak. No matter how science with invent things, they cant stop old age. Nice write up. Good luck to you