Newtons, cool weather, or forgot my phone?

I had committed to help a friend move some boxes to her new apartment later this evening. So I had to get a run in today right after work. I changed into my running clothes quickly and headed out the door. It was almost cold this evening. Or is it me? A co-worker remarked that now that we're old, it seems we lose our ability to fight off cold temps. I was thinking just that this morning as I reflected on last years attempt at the Bandera 100K trail run. It was 8 degrees at the start and I failed to wear the right amount of layers. I paid for it late in the run and dropped at 42 miles.
Anyway, I left for my run today in a long sleeve shirt and began running down the road headed to the trails. I was moving at a good clip. Cool weather seems to give me more energy. Feeling good and thinking, "these newtons feel good on my feet. They make me run fast!" As I hit the trails , I thought, "hey! I'm on call this week. I forgot my phone" Go Back? No. Just run faster! Made it to the 2 1/2 mile turn around and headed back home. Stretched on the porch, walked into the house, checked the phone, no call. Good. Checked my Garmin. Cool! Pretty good pace. Speed work today!
Oh, and I signed up for another attempt at the Bandera 100k on Jan 8th.