question: hi sir ,my name is katheek.iam from kothagudem mandal khammam district.i have previous history of bronchial asthama.i measures about 164 cms height,79kge weight.recently iam suffering with breathing problem(breathless ness).i met general physician in my town.physian told that iam suffering from exertional dysnea.how exertional caused,i want to know preventive measures to protect me from the above.so please kindly suggest me.