I'm 42 and perceivably healthy, I love sports, cardio, and weights. however I have stopped altogether due to this weird sensation that happens to me often when i do any physical activity. It's actually very hard to define. It feels like a sensation of lacking oxygen, like my heart is racing, or will race out of control. It also feels like the onset of a panic attack - cold clamy hands, shortness of breath. However it always goes away after a while and I feel somewhat fatigued. I'm very confused about this. I don't know if this is normal athletic training process or if I bring on the panicky feelings on myself by simply getting scared that something is wrong. I really don't know but I've quit exercising due to this. If anybody has some insight it would be greatly appreiciated. - Thanks