If you have a hard time getting your significant other to exercise, suggest hitting some balls together. Since this is more of a game than a workout, he or she will be more likely to go and play. Plus if he is a fan of watching baseball or softball on TV, he'll probably be psyched that you want to play.
If you're new to the whole bat and ball idea, pick up a plastic bat and some wiffle balls, soft baseballs or foam softballs. They'll move slower so you'll have more luck hitting them. If you've hit some balls in your lifetime, go ahead and buy a wooden bat and a few real baseballs or softballs.
Visiting the batting cages is really fun too. For a few bucks, you can work on your hand-eye coordination, strengthen your upper body, and have a few laughs when you or your honey misses the ball.
Fit's Tips: If you're both really into it, see if there is a co-ed baseball, wiffle ball, or softball league in your area. Not only will you meet some fellow active people, but it's a great way for you two to get into a schedule of working out together.