Age really is just a number

For an assignment, I had to interview someone who was 65 or older. I went to my grandma's (who is 82), with intentions to interview her. She is in early stages of Alzheimer's and broke her hip about 8 months ago. Her sister (my great aunt) who is 78, was visiting when I got to her house. I ended up doing my interview on my great aunt, and while doing so realized the great differences between her and her sister, even though they were only 4 yrs apart in numerical age. My aunt is very active at the senior center, still driving, and completley independent. My grandmother has had a great decline in activity, and relies alot on my mother for everyday activities. Watching them side by side, it was obvious how age really is just a number; they are only 4 yrs apart, though their abilities and independence are on opposite ends of the spectrum. I wonder what it must feel like to have grown up so close together all those years, been so much alike, and then all of a sudden have so much difference? Dementia and other diseases doesn't strike at a "set" age, nor does it affect everyone. It make me think, how old would I be if I didn't know how old I was? Would I feel alot older than I actually am, or alot younger? What things in my life can I change to make a positive impact on how I age?