All ages can enjoy this.
Designate four areas or just one if you don't want to move from spot to spot.
Draw the four exercises on a paper and show them how to do each exercise
Explain to the child that you will be doing each exercise until they hear you whistle, tell them or if they can count until they count till ten (you can up that if they are older and can count further)
Then move to the next exercise
You can join them too and become just as fit as your little ones!