what should i expect when i get old like the rest of you

You might have to spend time caring for your unwell spouse, as happened to me. Of course, it could be the other way about. In some cases, they both fall ill and have to take turns looking after each other. 

When you are young and healthy, you don't believe the 'in sickness and in health' bit nor the 'till death do us part' bit. I insisted on changing the latter to 'as long as we both shall live' but it's really the same. 

 

I've heard that taking up tumbling after 50 is a "hard road to hoe," but I'm 73+ and my abilities and my interests have remained extremely close---and I have been successful in adding to my abilities over time.

For those of us who "fulfill our vocation in time" the philosophers say that as we age (if we're doing it right) we move from potency to act---in other words, we become more of what we can be.

(Apparently, those philosophers were mostly old men who had a log of experience with personal aging.)

Go "bleep bleep bleep" yourself!!!

Hopefully, just a more experienced and more content version of yourself.  It's all up to how you look at being "old" and how you feel when you get there.  If you play your cards right, you won't lose your "edge" or sense of humor though.  Never lose that.