Our bodies become used to the demands we put on them. Sometimes doing something different can break us out of a holding pattern in our fitness. If you usually run, try swimming or stair climbing. If you usually play basketball, try soccer. If you usually do yoga, try a martial art. If you are a gym rat, try getting outside.
This can be true of everyone, not just adults. Kids need to be exposed to many different activities so that they can really know what they like. A lot of kids will have preconceived notions about certain sports and games. It is only after getting a chance to learn and play in a safe environment that they realize they actually like something.
Resolve to try something new with your kids at least once a month. Be willing to go outside your comfort zone!