Here's what I do, and I'm a terrible runner:
I jog probably twice/week for health and to get outside. That's really only during the spring and fall because the winters here might as well be Hoth and the summers might as well be the 4th layer of hell. I'm terrible at it, I never run at a PT test pace, and I skimp out all the time.
About a week before the PT test, I do push-ups and sit-ups once, just to remind myself that I can.
On the day of the PT test I go out and pass it. Because it isn't that hard.
I used to spend a few weeks trying to get myself ready for the test. I stressed about it. I found that none of that made any difference for my run time, which is by far my weakest event. I took my last 2 tests with no preparation at all, and I scored essentially the same as always.