"All inner resistance is experienced as negativity in one form or another. All negativity is resistance. In this context, the two words are almost synonymous.
"Negativity ranges from irritation or impatience to fierce anger, from a depressed mood or sullen resentment to suicidal despair...
"The ego believes that through negativity it can manipulate reality and get what it wants. It believes that through it, it can attract a desirable condition or dissolve an undesirable one.
"...The fact is, of course, that negativity does not work.Instead of attracting a desirable condition, it stops it from arising. Instead of dissolving an undesirable one, it keeps it in place. Its only 'useful' function is that it strengthens the ego, and that is why the ego loves it."
(from pp.98-99, Practising the Power of NOW by Eckhart Tolle)