I do like to exercise every now and then but do not have time to take it really serious since I work mostly at my computer. But I do find time every now and then to go and exercise harder on a little longer period, thinking that I'll strengthen my body but instead finding myself getting sick every time I exert myself. Some say it may be due to my immune system which is not used to exercise, so I was wondering can that really be the case? I don't think that I'm that inactive but if that would be the case what should I do? If the solution is exercise but I get sick every time I do it, is there any other way?