The other day when I was exercising (I try to exercise every day to keep my cholesterol down), I had a very interesting experience. I wish I could say that this was a unique experience, but it has happened a few times over the last couple years. In the middle of my exercise routine, my legs started to get weak, my heart started racing, my breath was rapid and I had to lie down to get my strength back. The first time it happened, I was really worried about it and went to the doctor. It has only happened 2 or 3 times in the last 2 1/2 years, so it is not a regular occurrence, but it worries me when it does happen. The first time I went to the doctor, he did not seem to be alarmed because the "stuff" stopped happening after a few minutes. I am not sure if it does happen again if I should go to the ER? Any thoughts?