Kids love to have fun. That's why they like computer and video games. Entertaining. That's why they like to watch television programs and movies.
If you mention them the word "exercise", all the thoughts of the fun disappear from your mind. The practice is push ups and jumpers. The practice is to endlessly laugh at an oval track. In other words, boring.
You do not have to. We did not have childhood. Of course, we did not have all our kind children, so we had to find something that was amusing. Most of our outdoor games were very powerful in nature. They're still there, they just did not play so often. : Take the bikes to the park and let the kids ride on the paths. As long as they walk politely for the passers-by, these trips are as useful and children are endlessly safer than riding on the street.
Find an organized sports team that your kids are interested in. Our area is baseball, softball and water polo. Schools offer volleyball, basketball and football. This will do more than exercise, teaches team-specific and fair play.
The memories I enjoy the most when the adult family members joined the game. My parents sometimes play and older cousins. I still hear my mother shouting: "Do not ring my tomatoes!" when we got into a horseshoe match. (The pit was right next to the garden.)
The people involved help to bring the family closer. It teaches that adults like to have fun and that this is the kind of thing life is about. It's worth the time.