Emily, I would also find it very hard to run, ride, etc. in the temperatures you experience. When I lived in AZ, I *never* dreamt of exercising outside, thus, I was a gym rat. I regret that I was so much in this habit, that I didn't use the cooler time of year (winter) to do more outdoor activity, because it took me a long time to become an outdoor person. I had lived in MA 10 years before I started cycling, although I had made a small (and I mean small) attempt at cross country skiing starting in 1991; fully dressed in layers of cotton , I may add! I also missed out on exploring some of the beautiful natural terrain near where I lived in AZ. Almost 2 years ago, DH and I went to AZ for his mom's memorial celebration. We did some hiking in a county park that I had never been to. Sure, it was not super close to where I lived, but still, only a 40 minute drive. I sincerely regretted this, but I just never would have braved the elements.
I think intensity is the key, too. I spent about 2 years in my mid forties burned out on the gym, doing less and less each time I went there, and gaining some perimenopausal weight (15-20 lbs.). When I started cycling at age 48, the weight started falling off, without too much of a change in my diet. I wasn't eating horribly, but I am much more "clean," now. Like ShootingStar, I have pretty much eliminated white breads and rice, except on very rare occasions. In fact, I try to even avoid all grains during the week. I don't think i could ever go totally Paleo, but adapting some those eating habits and adding in boot camp (strength and balance) has gone a long way in helping me maintain my weight and fitness. I haven't eaten junk food or lots of sweets in years, so that's not a problem for me. If I have dessert once in awhile, I enjoy it and get back on track.