Is An Inhaler Necessary For A Person Who Has Difficulty In Breathing?

hi, I have Tracheitis when i was young. The way the doctors said it sounds like it was linked to asthma. Whenever i fall ill, i have serious breathing problems and will be exempted from physical activities for days. Normal chores will get me panting and the only time i will be breathing fine is sitting up. Even if the illness is over, i will still have a period whereby i will have breathing problems and lack of ability to breathe normally. I have trekked hills over the years for around 2-3 times. Every time, i will feel breathless and breathe more unstably as compared to the others. I will be climbing a hill with the school this coming November overseas. What would be necessary for me to reduce such symptoms that i might have? Is an inhaler necessary, i really would want to climb that hill and not suffer that badly.