I will run down to 22 degrees. But I've gone for walks in -20. I have a lot of gear from Eastern Mountain Sports, Nike, New Balance for running but running outside in the winter means a ton more laundry. I have a spin bike in the basement and I can just go to the YMCA and run on the indoor track or the treadmill.
I have balaclavas, ski goggles, tights, tops, baselayers, mid-layers, wool socks, lots of gloves of varying thickness.
I also have neuropathy as a result of chemo. It's like Raynaud's disease where your fingers and toes buzz or go numb in cold temperatures.