Heart or lungs?

I can't do anything slightly straining without feeling unreasonably out of breath or nauseous. Even when I was a gymnast and diver I have never been able to run, jump, lift, whatever without feeling like I'm going to suffocate. I can't run or wrestle without getting awful flegmy caughs for an hour. My mom smoked but I left years ago and if you ask me 5 years is enough to get out all the nasty 2nd hand smoke. I'm always tired and COLD, God am I cold. I'm just tired of always feeling like I live in the body of someone who has never moved off the couch and only ever eaten. I need to know what this could be or what I can do. I do exercise so I don't get how I still feel so crappy.