If you have asthma it is paramount that you exercise, because the benefits of exercise coupled with a healthy diet not only help you lose weight, but it can help you better manage your asthma.
Even if it's just a simple walk, exercise has many benefits. According to the Mayo Clinic:
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My son is an Asthmatic and Exercise does help. You would never know that Michael has Asthma. He runs Fast and Longer that is "Healthy" Sister.
Our best Exercise is Swimming. We "Play" around to the Pool up to Three Hours.