I agree with the asthma/lung thing, especially if you lived in a smoking household for nearly your whole life!! Don't get me started on that one!

I used to have asthma. I don't know if it was exercise-induced or allergy-induced only (I know allergies were part of it), but I've had a few bad attacks off the bike and just plain discomfort on the bike. In fact, when I was racing (I sucked) when I was your age, I ALWAYS felt like I was out of shape, I always got dropped. It wasn't until years later that I was diagnosed with asthma and got an inhaler. All of a sudden I was able to breathe on those hills! So get that checked out ASAP. If you have carpets where you live, either remove them or move to a place with wood or tile floors as soon as you are able. Removing carpet from my environment pretty much cleared up my asthma.

Don't discount your commute--it's GREAT to live close enough for a bike commute! Use your commute just as you do--for transportation, relaxation, and building a solid base. The more you are on your bike, the better you will be, and the better the world will be!