There is a test you’re supposed to do to see how you’re aging. It’s called “sit-to-stand” and involves setting a timer for 30 seconds, then standing up and sitting down as many times as you can. The exercise assesses your balance, your heart, your leg strength, and a bunch of other things.

Here’s how it goes: You sit on a straight-backed chair, cross your arms over your chest, rise to a standing position, and sit back down. At my age, the average number of times a woman can do it is 10. The first time I tried, I did 14 (the average for someone a couple of decades younger), but then realized I was sitting all the way back instead of immediately going into another repetition they way they tell you to, so I could have done more.

I rested a bit and tried again. I could tell I was doing a lot more this time. Then I glanced at the timer and realized I had forgotten to start it. Oh, well. I decided to try again later on.

No matter what some gaunt person with good genes who runs marathons at 90 tells you, aging is not just a state of mind. Also, a lot of our little limitations are not at all related to age. For instance, my frequent lapses of memory and attention have been happening all my life, and don’t seem to have gotten better or worse. I would have forgotten to start that timer at 14 or 34. Trust me.

But my knees often hurt, especially when the barometer is high, and I take my time getting on the bus. I hold onto the bars when I’m moving around in the bus because my balance is poor. I have good old-fashioned lumbago, like a lot of people much younger than me. (That’s low back ache, for those of you who don’t read 1930s detective novels.) My eyesight is poor, despite the cataract operation, and my hearing is bad, despite the very expensive hearing aids I wear. I don’t have a good sense of smell. My hair grays steadily.

Sometimes, though, people glare at me when I sit down in the senior citizen seats.

That’s because despite my wrinkles and the gray hair, I don’t look as old as some of the other people in those seats. I disconcerted the heck out of someone the other day when I said I have a senior citizen transit pass. People think they know what I’m supposed to look like at my age, and apparently I don’t qualify.

When I do find out in bus conversation that someone is my age, they do often look a lot older than me, but then they often have walkers, canes, or rollators, and their faces, originally more delicate than mine, have softened. Also like me, they are on the bus because they don’t drive any more, so it’s a self-selecting group. A couple of women in my senior citizen classes look younger than I do.

I was talking to my HVAC tech just now and he’s probably in his fifties. He’s had a broken neck (football, probably), surgery on his shoulder joint, and a major colon operation (removal of a section) and he and I look similar in age even though he’s maybe twenty years younger. But we both got up and down the stairs pretty well. He was startled when I told him what my age is; his mother is 81 and in bad shape.

Yes, I chatted at length with him, mostly because I’m a suspicious soul. I figure he was replacing a heater that didn’t actually need to be replaced just yet. But then I’m 74 and I might live a good while longer, expecially if I stay good at that sit-to-stand exercise, and it would be nice to have a working heater if the economy goes sideways. The heater was old enough, even though it wasn’t at the end of its life. Just as I’m old enough, except I’m not going to get replaced.

I guess what I’m saying is age isn’t all in your mind, but it’s also not entirely in the numbers either, and it isn’t in your joints, your muscles, your colon, your face, or your brain. I don’t know where it is.

Just now I went and tried the test again, and did 18 repetitions. I’m gonna live forever. Unless I keel over later today. It doesn’t tell me much, in other words, but it was kind of fun trying to do it.