I'm 53, 180lbs, moderately active, just started a new exercise program. I have "reactive airway", so my difficulty breathing may be related, but twice now, after working out I've noticed that for several hours afterwards I have a hard time getting a good breath. I don't feel overly taxed. My heart is not racing. I took my inhaler and it seems to alleviate the symptoms somewhat. I'm concerned because of my age and weight that my heart may not be in great shape. I had a stress test a few years back and it was "great". Should I be concerned?