Although I know that heart palpitations do happen (and also that this is normal and not dangerous), sometimes I THINK I'm having heart palpitations when I'm really not. I figured that out once when suddenly, in the midst of feeling all panicked about "heart palpitations" I was having, I got the exact same sensation on the other side of my chest! SO... unless I have 2 hearts, what I was feeling that time must not have been heart palpitations! Haha. I felt pretty foolish. But it taught me something. Now, when I feel heart palpitations, tightness in my chest, etc., I try to remind myself that a) if it IS a heart palpitation that's normal and not dangerous... it can't make me pass out, and I'm not going to have a heart attack, and b) it may not actually be heart palpitations I'm feeling at all! It's probably just muscle tension in my chest muscles or something. Sometimes I still don't believe me, but other times it helps.