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. Mostly I'm talking about euro-games like Carcassonne, Race for the Galaxy, Power Grid, Pandemic, etc, 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).