Mentioned this before but I feel I should elaborate on it a bit more. Once I'm done with the Shiny Celebi special research quest, I'm taking a break from Pokemon GO. Not because I'm tired of exercising (though taking a break every once in a while for one's body to adjust is good for exercising I hear), but because a medical condition that the winter weather isn't kind on: dry skin. The winter weather probably causes everyone's skin to not be the best, but for someone like me with dry skin it seems to be worse. The cold air dries up my hands and I'd have to put ointment on it to help heal it. If I don't, the skin becomes dry enough to cause small tears to appear in the skin. The tears aren't too bad if you're wondering, just painful annoyances that need to be dealt with. The rate at which the dry skin, well, dries also seems to be quicker outdoors than indoors, so that seems to be a good incentive to take a break from playing GO. I've had dry skin all my life, but it seems in later years that my skin is more susceptible to air temperature as I don't remember this being as much of a problem in my childhood, though it's possible I may have forgot as it's certainly been long enough.
So in short, I'll take a break from GO until my skin is 100% again. Plus winter isn't exactly the best time to spend an extended time outdoors anyways even without a pandemic, as you could still catch something just from being exposed to the elements like that. I'd say spring and autumn may be the best times to play the game: not too cold or too hot, but just right.