Just so we're clear on this, I'm the guy you've driven past, merrily running around town when it's like 20 below zero out. I don't know why God wired me that way, but I'm a runner through and through.
I'll grant you this: it does get hard to motivate myself to run when it's bone chilling cold outside. I almost always find a way to get myself out to do it.
The times I most dread going for a run are (1) approx. 2 days after it snows and (2) right after a hard rain. Here's why. With the snow, I normally run on the Constitution Trail (or here or here), and it's way too easy to get sprained ankles from running on hard, crusty, icy and uneven ground.
After a hard rain, I just don't like to run on all of the worms that have crawled onto the pavement to avoid drowning. Yep, it's true.