Your father, Dr Ee Peng Liang, was a very active volunteer even at an advanced age. My father was driven by a personal mission to serve the community. It was a calling and that was the source of his energy. He was a God-loving man and his service was his dedication to God in prayer. He turns to God for guidance, encouragement, and energy.
Nothing can beat that for faith can move mountains.
Certainly, poor health would be the most negative aspect of ageing. As long as I can be of use to the community, I can maintain a high spirit. All human beings want to feel useful. The only thing that stands in the way of active ageing is poor health. I try to maintain an acceptable level of fitness through Tai Chi exercises and regular visits to the gym.