I was in this situation for more than a decade up until a few years ago. Was diagnosed with General Anxiety Disorder (GAD). I used to have panic attacks after discovering my heart wasn't beating at the resting rate according to Wikipedia, or when my skin felt a little dry and I thought I was having a heart failure. But once I started taking antidepressants, it almost completely went away (in addition to other techniques to take my mind off of myself when needed).