Performance anxiety

So, I am taking a couple of classes right now to keep my brain alive. I really enjoy both of them, and am actually taking them for a grade. This means that I have to write papers. I haven't written a paper since college - back in the days when you had to print them out and turn them in by hand. These days I guess you just email them in.

I'm a little daunted. My first paper shouldn't be too hard. But still - it's been so long! Will it be like riding a bicycle? Or do I have to learn all over again how to construct persuasive arguments? Back in the day, I did pretty well for myself in school. But I have changed - I'm older - has my ability to absorb and retain new information or my attention span diminished? Of course, I will have to pull this thing together in small chunks while Munch is napping. That's a big extra challenge right there.

I've always looked back to my academic record to bolster my self-esteem. As I consider going back to school, I worry that I won't do as well, and will dilute that record. I am completely freaked out at the idea of taking the GRE or any other standard exam. I almost reject any plan that requires me to do so. I mean, for godssake, that thing has MATH on it. I always did well in math, but that was a lifetime ago. Getting tested on that stuff would mean that I would have to relearn it. Even my ability to do basic computation in my head has diminished, since I don't have to use it that often.

What happens if I get started on all of this stuff and find that I'm just not as smart as I thought I was? What do I do then?