I have the same thing everyone above is describing. I know how discouraging it can be to want to exercise and then get that debilitating headache afterword!!! Once upon a time I was a cross country runner, and very fit. I am now 44 and these exercise headaches have been going on since about age 30. I ended up gaining weight because I couldn’t work out. I am now losing the weight, through diet and moderate exercise. I have finally come to the realization that I may not be able to get the runners high that I used to enjoy, but I can still walk, do the elliptical moderately, do pilates and yoga, and do weights at the gym as long as I’m careful NOT to OVERDO it. I can even jog about a mile and a half during temperate weather (not too hot), usually spring and fall is best, and winter if not too cold. If I go further than one and a half miles, or if I try to go too fast, I will get a headache.