In DnD 5e the barbarian rage is somewhat different from it’s 3.5e counterpart, but the thing that most confused me is the need to be actively part of mayhem and destruction at every round to keep being angry (emphasis mine):
Your rage lasts for 1 minute. It ends early if you are knocked unconscious or if your turn ends and you haven’t attacked a hostile creature since your last turn or taken damage since then. You can also end your rage on your turn as a bonus action.
Now the question is, can a Barbarian (with or without shield) punch/stomp/bite/headbutt itself to recieve damage and maintain rage? To me, it seems it’s possible by RAW, but I’m not sure about RAI if an unmissable attack (I refuse to think that you can miss hitting yourself if you are not heavily drunk) with the lowest melee damage possible from a Barbarian can keep you raging for the full duration.