Many couples don’t exercise together because one partner is much more fit than the other. Riding a tandem bicycle is a great equalizer. The amount of work you do on a bicycle depends on how hard you push on the pedals. Pushing twice a hard on the pedals takes twice the work, so a world-class bicycle racer can ride with a novice and still get a good workout. Even a beginner will be able to keep up with the spinning pedals, no matter how fast they go. The less-fit partner just applies little or no pressure so he or she will not get tired. No matter how hard one partner tries to leave the other, you will always be together.
You can go faster together than the faster person can go alone. The more experienced rider sits in the front seat. If both are equally good riders, the taller one usually sits in front. The person who sits in the back copies the motions of the person in the front. At first it may seem strange not to have any control over steering, shifting or braking, but the you have the big advantage of being able to exercise only as hard as you like while enjoying the scenery.
Many cities have tandem bicycle clubs that organize rides and social events. They welcome newcomers and will give you lots of help when you’re getting started.