Am I ready for a sub-20 5k??

1. How fast can you run a 5k right now?

2. How long have you been doing 25-30 mpw?

Since you previously broke 18, 25-30mpw should be plenty to break 20 without a particularly large amount of targeted effort. Usually around here when people say 25-30, what they really mean is they recently ramped up to 25...

I've been running 25-30mpw since about November, although I have had a few off weeks of about 15 miles or so. And last time I ran a 5k was in February I ran 20:45. I plan on taking another crack at it here pretty soon.

With your PRs, and being back to running for a couple years now, and doing some structured workouts, you're probably there already. Just hop in a serious race, go in rested, and don't do anything stupid in the first 800m. It might take a couple races to get used to the feeling of racing again.

You've still got a lot of places to go with consistent training. There's no reason you can't eventually beat all your PRs.

I agree with the previous poster: you are 27, not 50+; you used to run 17:XX and have been doing some reasonably consistent training with intervals; from a physical standpoint you are probably already there, you may have just lost the feeling for racing. There is no reason why you cannot run faster than in high school (with proper training).

If you can do 1-2 extra 800m rep at 3:10, you are probably there, especially if you are running the interval workouts alone.