I love being outdoors, more so in winter than summer. So even before I moved south winter was never a reason to stay inside. If you don't want to ride a road bike trail running , XC skiing, snow shoeing, are great winter activities, but with no snow or some snow MTB riding is also great. When I lived up north one of those was always a good choice.
Summer may tempt me to stay inside, but I just get out early (before dawn if necessary). I find that while I hate hot weather I can tolerate it as long as I get out early and get acclimated early in the season. If I avoid the heat in the early season and suddenly try to acclimate when really hot weather is in full swing it is tough and I might stay inside and work out on the rowing machine. That has happened when if I was laid up with a surgery or injury in the late spring/early summer.
Here in Tallahassee we only get a few days with lows in the teens or 20s. Lots of mornings in the 30s though. I really don't mind those temperatures at all so winter here is great. An 18 F morning is way nicer than one with a heat index 90-100+ F. So basically summer here sucks and winter is nice IMO.