Ah ok thanks, im going for AC op, not a soldier 
Every course I've been on the runs have been longer than they were anticipated. This doesn't really bother me as I enjoy PT, however it was unfortunate as it would screw everyone else over and cut int our ablutions and meal times. How? It because of people like you, even on my DP1 after people had been through two courses, they still would fall out of PT.
So what ends up happening, is we can't leave anyone behind, so we would run and around the 3/4 mark of the run people would fall out. We'd see that, turn around pick up said individuals and watch them fall out again and again. What was once a 5km run turns into 6km, and that takes away five precious minutes of meeting our timing for breakfast. If we are late, not only are we doing pushups, we now have even less time to eat. At the end of day it doesn't matter but it is frustrating to say the least. All of this could be avoided if people would show up courses physically fit. No one is asking you to be able run a marathon, but is it really to much to ask for you to be able to do 5k in under 25? Look I was just like you, I did nothing for cardio, played hockey in the winter and soccer in the summer that's it. But I played at the lowest level as my cardio was garbage. When I started that couch potato - 5k program in the summer I could barely finish the first day I was so tired after. But I knew that I was joining the reserves and had a swear in date for Sept, so when I showed up to basic I had no problems with the cardio.
Don't worry, when you need help from your course mates they won't forget.