You know that exercise is good for you, right?  But do you know why?  It's not just that you feel better (though you do, once you get a routine going) but that exercise actually changes your brain and "turns it on."  Dr. John Ratey, who knows a great deal about the science behind this topic, explains the connection between exercise, learning, attention and more in this TEDx talk.  It's definitely worth a few minutes of your time!  And it's very relevant for couples.  Want to create new habits?  If you are both exercising you improve your ability to succeed at a very physical level.