a lot of times i don't feel like i'm getting enough air in my lungs and i get winded early on. it feels like i'm getting about 90% use of my lungs, and i can't quite fill them up all the way. anything i can do about this? or will it resolve itself with more training? i don't smoke and i've never had an injury that would hinder my breathing. my bike fits fine and my form is okay as well. any ideas?