1) Try teaching someone something useful.
2) Try starting a conversation with a stranger, someone you wouldn’t normally converse with (chatting with the waitress doesn’t count… chatting with the person in the next booth might).
3) Try emailing encouragement.
4) Try writing 200 meaningful words.
5) Try doing something that will still matter a year from now.
Tip: you might be able to pull off two or more of these at once. Bonus points for doing them all at once.