Remember the things you wanted to do and the places you wanted to go as a kid. Put those things in action with your children (if they're interested), as well as places and things they suggest.
Take them to a beach to collect seashells and to build sand castles.
Save for a trip to Disneyland or Sea World.
Try to expose your children to as much fun as possible.
Being a child only comes once.
Help your children enjoy it by tapping into your own childhood desires.
*Note: The author's "Positive Parenting" method has grown and evolved into what she dubs "Upstream Parenting."