When I was young I could string a long a couple of 5:30 miles.  I wasn't even a distance runner but a sprinter.  Now since I drink a ton of beer on weekends and I'm 50 I wonder what I could run a 5K.  I normally run 2 or three miles twice a week or so in addition to my lifting.  Last week I started running 5 slow miles a day.  Running at 190lbs isn't the same as running at 155 to 165lbs.  I'm looking forward to what I could do now.  My goal is to break 21 minutes but in most 5K's I would be looking at the back of a lot of real runners leaving me in the dust.