Tony Soprano: They gotta keep moving, or they die---they can't breathe or somethin'.
Dr. M.: There's a psychological condition known as alexithymia---common in certain personalities. The individual craves almost ceaseless action, which enables them to avoid acknowledging the abhorrent things they do.
T.S.: Abhorrent? [pause] What certain personalities?
Dr. M.: Antisocial personalities.
T.S.: [pause, reference to future brother-in-law, then] What happens when these antisocial personalities aren't distracted from the horrible shit they do?
Dr. M.: They have time to think about their behavior---how what they do affects other people. About feelings of emptiness and self-loathing haunting them since childhood. And they crash.