The physical demands of cycling is that it actually lowers your immune system, and you expose yourself to a tremendous amount of elements - so certain people might get a chronic overload and develop, say, bad asthma.
What people need to know is that asthma isn't a minor 'wheeze-disease.' It kills over five thousand people in America every year, and I could've been one of them.
I don't know whether other asthma sufferers find this, but I've noticed that even when I've got my asthma under control, I often develop another problem such as an ear, chest or sinus infection and sometimes even joint pains.
I miss being able to play my instruments - I'm too much of a physical wreck these days. Playing the vibraphone gives me backache, leg ache, and everything-else ache, and the asthma means I no longer have enough puff to play harmonica.
