LOL the gym part is definitely a mental issue, though I can see why getting up and going to the gym is like a commitment to actually exercise.

At least for me, public transportation would only get me so far, so even if I did that, I'd still end up walking/biking a fair amount. It's not just feasible if you are in any sort of hurry, and have other means of transportation.

I think for many people in North America, public transportation isn't even an option, like any rural areas, and even new suburban areas.