I enjoy playing board games with my friends. We have been having board game night every Thursday for almost 5 straight years now and it is one of the best parts of the week. Specifically, I'm talking about games like Carcassonne, Race for the Galaxy, Power Grid, Ticket to Ride, etc. Lately we've been enjoying a bunch of collaborative games like Pandemic. But I'm never above a good game of Cards Against Humanity or Texas Hold 'Em. I also like the occasional pub trivia night, and I've been doing a lot of puzzlehunts lately. These are things like BAPHL or Mystery Hunt.
On the outdoors front, I like going sailing a lot in the summer and ice skating in the winter. I find both quite relaxing, but both are better with someone else. Also, biking (for fun, exercise, and transportation) and running. I've run a few relays across the width of Massachusetts and even the Boston Marathon as a relay (long story).