I've lived with asthma for longer than I can remember, and even though it has abated to a degree the pesky debilitation is still hanging in there. After at leats two decades of dealing with it, however, I've learned that there are certain ways of not only controlling my asthma, but making sure that it doesn't kick in in the first place.
I can always tell when an asthma attack is imminent. I'm sure just about any sufferer can: the chest starts to tighten, breathing becomes more restrictive and your energy level drops to near zero. How and when the asthma invades my day varies with the circumstances - sometimes a massive influx of dust does the duty, sometimes it's an over-exposure to smoke or other, more natural inhalants, and sometimes it's just from an excess of activity. Pushing one's lungs to work harder than they're capable is a sure path to the hyperventilation that causes asthma attacks.
Normally sufferers run right for their puffers. Can't say I blame them: that was my knee-jerk reaction, too, and when I get really bad it's still the best option. Yet I try to limit my inhaler usage whenever possible, as there are lots of alternatives, many of which can be employed as soon as you feel the attack coming on.
Usually the best defense is to STOP WHATEVER'S CAUSING THE PROBLEM! Seems simple enough, but you'd be surprised how stubborn some people can be. If you're out for an intensive jog and your breathing's getting more ragged than usual, give it a rest for a while. A bit of wounded pride at having to stop short is better than dragging yourself home sounding like a rusted door hinge. And, if it's the environment that's hitting you hard, move somewhere else. I've stopped being polite about not offending people, especially around smokers. If you're making me wheeze I'll part company with you.
Sometimes, though, the attack is inevitable, and though the puffer is usually an option I find it isn't always. In these cases, deep breathing is the path to respiratory freedom. Slow yourself down, take a seat and take some nice, deep breaths. Try to get yourself in a rhythm, concentrating more on the act of breathing than the tightness in your chest. Soon enough, that tightness will be gone, or at least have eased up enough that you can continue about your day at a slower pace.
Asthma is an ever-present aggravation. But it need not control your life, and with some willpower and a bit of judicious logic you can avoid being plagued by constant attacks.