The Buddha's image for this teaching: being struck by an arrow, then striking yourself with a second one. The first arrow is the pain itself: the criticism, the delay, the ache. The second is everything you add: replaying it, resenting it, narrating what it means about you. The first arrow was never up to you. The second one always is. Today, when something stings, look for the gap between the two. You don't have to be a sage to drop the second arrow. You just have to notice you're holding it.
Now, the well-instructed disciple of the noble ones, when touched with a feeling of pain, does not sorrow, grieve, or lament, does not beat his breast or become distraught. So he feels one pain: physical, but not mental.
Samyutta Nikaya 36.6, the Sallatha Sutta "The Arrow" (trans. Thanissaro Bhikkhu)