If you're tired you can take a powernap, take a shower, exercise, cook.
If you're bored, maybe try creating something, anything, music, drawings, painting something, just randomly typing away, taking a walk and listening to an audiobook, taking photographs.
This one I heard of but haven't done yet: walk in a city, at every crossing flip a coin or throw dice to decide which direction you'll take. You could also do this in the subway, how many stops till I get out? You're bound to see some interesting things, so take a camera.
Good luck
