Hi! I just starting to get into more aerobic exercise recently and I am out of shape from being seriously ill for the past four years. I have done a lot of daily walking, but nothing that got my cardio to a training level, or reaching my max heart rate. Now when I do this, via a bike trainer for now.......sometimes I get the ammonia smell after exercising. In the opinion of the fit people on this group - is that a sign that I am overdoing it? Should I back off to where I don't have this happen? I am still kind of fragile, and trying to walk the line between getting fit, and not over stressing my body, esp. brain and nervous system. Thanks!