Just did this on the Magic last week (we just got off the boat Friday). Here was the process.
Met in Diversions between 8:30 and 8:45 where you signed up and got your number to pin on. We met by the bike rentals which is where the 5K started where they did roll call and showed us the course at 9:15 am. The time clock started and we were off. I was the only one who started off walking (but didn't take long before I passed those who started out running/jogging). The course is simple. You go down the airstrip, around the loop for the observation tower, back to airstrip towards serenity bay, turn around and take a reverse course around the observation tower and back to the start line. Once there, you get your medal and they mark off your name. I walked the entire way except the return loop around the OT which I jogged (because I couldn't stand the scenery and wanted out). I finished just under 40 minutes (37 and some odd seconds). That was it. Glad I did it. I would suggest if you have an i-pod or some sort of music source, take it. It didn't seem like 3 miles to me so perhaps that's a good thing. There were some who were big runners and others who struggled after they got started. I didn't feel so bad starting in last and finishing well ahead of others who started out strong.
Let me say this though. It was HOT/Humid! By the time I finished, I had a layer of sweat all over. I looked like someone had covered me with a shean of glowing body paint. It was a cloudy day in the 70's. So I can't imagine what that would have been like in the summer with sunshine. They provide water at one point which is at the entrance to the loop. I had my water carrier on my back which I was happy to have. So for those of you doing this in the summer, drink your water.
Now a note on that loop to observation tower. It's the most boring loop! It's nothing but greenery around you and you see nothing else. Other than that, it went by pretty fast.
L