Neuroscientists describe the brain's "negativity bias":  we cannot let go of what we perceive as negative, criticism or something "bad".    Given that we are wired that way, it behooves us to make a practice of taking in the good, noting what is going well.  Make a point of taking in the moments of gratitude, accomplishment and joy.  By focusing on the "good" for 20 seconds we can imprint some positivity and begin to shift our mental playing field.