In HS I thought I was really out of shape because of my heavy breathing during exercise (now days I am actually out of shape) until I went to the doctor to find out if I had something wrong with me. They did a few tests and diagnosed me with exercise induced asthma. Basically, once I start exercising my lungs are only able to hold about 60% of their capacity when I'm not working out. A quick hit inhaler brings me up to about 80%. It's an excellent excuse for being out of shape aside from the fact that inhalers are pretty dorky looking.
I have the same thing. In high school, running sprints in football would absolutely kill me. However, during wrestling season I never had a problem because it was more muscle fatigue than anything. Nowadays, I still suck wind in basketball and soccer pick up games and its kind of embarrassing, even though I know for a fact I work out more than any one of my friends.
I totally agree with the power lifting suggestions here, but most gyms I've been to don't have platforms for them. Should I just go out in the open in the middle of the gym and do a power clean? Seems like I would get yelled at by gym nazis.