Ok, some backstory: So, I'm enlisting for the Army, and I haven't ran in quite some time. Or any sort of cardio really. A couple years ago I biked across the country, and though I haven't been nearly that active in awhile, I'm still not terribly out of shape, I have a wicked metabolism that keeps me pretty skinny, and I move a lot.

Well, I've never really been a big fan of running, the muscles in my legs take to it just fine, but my lungs never feel up to pushing it. I get this feeling like the passageways into my lungs and maybe a bit of the lung itself are freezing. It happens even when I'm inside a gym and the air is nice and toasty. Is there any way for me to avoid this feeling/is it natural? I can run slow all day long. I can bike pretty much all day long too, but it's a lot harder to get the same strain on your lungs while biking than it is while running.