There is a 15 miler in my area (Charleston Distance Run) that I've never done but always wanted to.
I'm 39 and used to run the road race circuit. I'd do about 30 miles a week with a lot of speed work.
For the past couple of years, I've done some fitness running, but mostly just using the ellpitical at the gym and a lot of weight lifting. I can run about 3 miles right now.
The 15 miler is over Labor Day weekend, so I have about 4 months to train. Is that enough to be able to handle the distance? I don't mind walking every now and then just to finish.