My son was diagnosed out of the blue at 18....he is a very keen sportsman and has always managed to run really fast, play football really well etc etc, it came out of the blue after a very bad cough refused to clear up after antibiotics. He still plays all his sport and manages to keep everything under control with his inhalers even while under my radar at university.
My daughter on the other hand has had episodes since a small baby, some of which have been pretty scary, and I'm finding it very difficult to get it through her daft brain that just because nothing too bad has happened for a year or so, taking the brown inhaler is incredibly important, she is 16 and obviously knows more than her mother
. Her asthma appears to be seasonal and early summer pollen related.
The most important thing is to take the preventative, and so keep everything under control.