It's hard enough to transition from a sedentary life to a life of fitness without going it alone, or worse, making small-talk with someone you barely know. It's often awkward and uncomfortable to begin a workout program with a colleague or neighbor. But, if your workout partner is someone who has already vowed to stay with you through thick and thin, you're more likely to stick with the plan. You already know your sweetheart's style, how far they can push themselves and how far they'll allow themselves to be pushed by you. In addition, they know the same about you. How important is that? Married couples who work out together are almost seven times more likely to stick with a fitness program than couples who don't [source: Keefe].