There are plenty of free and low-cost outdoor activities for kids that also come with great health benefits!
Go on a scavenger hunt. Try a theme-based scavenger hunt, such as spotting different animals, things you would see on houses, yards, roads, etc.
Gardening. Get the kids involved with planting flowers and vegetables and taking care of them.
Go camping. Whether camping in the backyard or at a park, there are lots to do when camping outside.
Backyard games. Set up an obstacle course using sporting equipment, sticks, rocks, and anything else they can find outside!