Attend free exercise and yoga classes year-round at fitness centers, community parks or recreation centers, and through local personal trainers. Apparel companies such as lululemon athletica make it easy for people to search at lululemon.com for a local gym or trainer offering complimentary classes. As the temperatures fall, look to cold-weather activities such as camping, hiking and skiing.

In the spring, try an activity you both enjoy, such as gardening, or head out in a canoe for a calming day on the water. Activities where you can act as partners and don't have to keep up with each other are best. "You want to be in the same boat, literally and metaphorically," Casey says.