I had mild childhood asthma and to this day very occasionally get slightly 'raspy' breathing due to heyfever, cats or feather pillows. I therefore have a blue inhaler in a drawer somewhere but can't remember when I last used it and I won't be replacing it because my symptoms are very mild and disappear within minutes of removing the cause.
I have never smoked. I played sport throughout my childhood and still do, and I've never had breathing problems on an aircraft. I don't know what the rules are but I have a Class I Medical and my peak flow and lung capacity results were above average.