Getting Committed...to Exercise

I was thinking of signing up for a race for exercise motivation. The race route pictured here is for a local race that I've never done- partly because the locale is super hilly and starts off with a pretty big hill (and I'm always at my worst before the 10min warmup time) and partly because- back when I did races, there was a race in my own town (that was flat, overall).

I'm not sure about signing up cause the whole thing is in a few weeks and while muscles supposedly have memories and though I've been exercising more lately, my muscless seem to be mainly remembering lying on the couch and walking over to the fridge.

If I don't do this one (I WILL attempt training for it- run walking at least 3 times a week), I think I'll sign up for one later in June and not stress the time I do it in. (Whenever I say that, I always start feeling competitive and try to better my running time. :P) I don't want to give the impression that I was ever fast though! I think my fastest 5k was 28 mins?