I have done five, which is about one a year since I started running. I have knocked about a minute off my time (not my pace, alas) in those years, showing my dedication to the slacker philosophy. Organized runs are a lot of fun, and I think there is a "bib effect" from the atmosphere, official timing, and permanent record that improves performance. I finished second in my age group on Thanksgiving, and for the first time took home a little prize in addition to my finisher's medal. You should sign up! I bet you can maintain an 8-minute pace for three miles, as long as you save the cookies and candy for the finish.
Well I did the 5k today! Thanks for encouraging me. I came in at 8:08/mile, and while I was hoping for a sub-8 minute pace, I'm still pretty content with it. I hiked 15 miles yesterday and am admittedly a little sore from that still, so all in all not bad. It was really nice doing the organized race. I may look for more of them and work my way up to a 10k and maybe a half marathon. I'm not the quickest, but I feel OK at my pace.
That's great! I bet it was the mistletoe station that held you up. It's always good to have a target for next time, and the with the 5K distance you can always tell yourself that with a little more push, you might have gotten down to the next whole minute. I might try to sneak onto a track tomorrow to make an effort for the Runkeeper Global 5K.