Had asthma since before I knew what I had. Other stuff, too... on a *good* day, I'm working with 60% capacity. On a bad day, I don't want to know. Not good. So, the bad news is I run out of gas (oxygen) quickly under load but the good news is that I recover very, very quickly. Inhalers only get me so far so I've learned to know when to pull over and stop for a minute. It takes me longer -a LOT longer- to climb that hill but climb it, I do.