Trying to let things go.

When someone makes me mad or hurts my feelings, It seems to hang over my head for days. Others tell me, "just let it go!", and "who cares!" But strangely enough, I seem to care too much I suppose. It's perfectly normal, in my opinion, to value what others think. However, I seem to hold on to the negative more so than the positive. :/ Something I need to work on.