you can forget stuff, and it's okay. When a plant comes up in the garden that you never saw before, even if you have the tag that says you planted it, it's always a pleasant surprise. and when a volunteer plant appears, you can take full credit for it being there.
You and your friends can tell each other the same old jokes as if they were new, and everyone laughs as if they never heard it before, probably because they have no memory of having told it to YOU three days ago.
Books read years ago, so long ago that the plot resolution is a gentle surprise, are always fun. What isn't, is realizing your favorite books are now the books of a much younger person, and no longer even readable.
You can be cranky, and its 'cute'. You can actually think, if not say, "now see here, young lady", and know that in five years or so you can say it too.
You don't have to keep up with new technology. And if you do, people are startled, which is always fun.
The day I realized I was older than most if not all of the doctors, dentists, and policemen, I stopped being nervous about any of them. We are now eye to eye.
Younger waitresses are often so unsure of how close you are to Senior Discount time and so nervous about insulting you, they often give you the discount anyway. I LIKE that one.