Go for a hike. Hiking will give you an excellent activity to get some fresh air and experience the outdoors with your children and, if you have any, your dogs as well. It will give you a relaxing place to get exercise while also sparking a sense of adventure and exploration.
Run or bike for a cause. Sign up, with your children, for a charitable race or event. This will not only allow you to have a great game day experience but will encourage you to train with your children leading up to the date of the event. It will be much more engaging than just the big day, as you will also want to go on runs and train together leading up to the event. Find a cause that you and your children agree on and are mutually compassionate about, that way you are both propelled and bound by the same end goal and motive.
An example of this type of event includes Run for a Cure--an event raising money to support breast cancer research and a variety of different activities with specific fundraising goals.
Start a family or neighborhood sports league. This, of course, can range anywhere to exceedingly casual and improvisational to more structured and scheduled. Choose a sport that you and your child both enjoy, or switch sports every week. Find a communal space to play, whether this comes in the form of setting up a makeshift kickball or baseball diamond in your backyard, or walking to the nearest publicly accessible basketball court.
Join a gym together. Depending on what age your child is, this could be a good option. By joining the same gym, you can carpool and do your independent workout, or even do a similar workout that includes a lot of partner exercises.
Join a class together. There are so many different types of exercise and fitness classes that it is difficult to imagine that you and your child would not be able to find one together. They are also geared for all different age groups, so this is an excellent option for any and all alike. It shouldn’t be hard to find an intersection of interests, or even to try a few out to find what works for you. Yoga, kickboxing, cycling, or water aerobics are all good options that are commonly available.