I tagged along on another trail run--about 4 miles, which isn't nearly as hilly as the one I'm doing on Valentine's Day. It was about 30 degrees and yeesh, it felt like the freezing temp that it is. I still struggled and still feel like I was gasping the whole run. For what it's worth, it would be awesome if I could maintain this 7:25 min/kilometer pace (it's about 12 min/mile pace) for the run on Valentine's Day so I could meet my goal to do a 5K under 40 minutes, but the extra hills on the actual course may wrench that up a bit.
We'll see...in less than 7 days, I run that 5K.