Children love a challenge. They enjoy the sense of mastery over their body and its emotions, especially fear. As they play, they test their abilities, giving themselves new goals and challenges to master. Mastering challenges results in giving children a sense of personal power and a satisfying feeling of accomplishment.

A Los Angeles afterschool program, A World Fit For Kids! (WFIT) is a nonprofit organization that utilizes an award-winning mentoring model in disadvantaged communities in order to reduce childhood obesity, increase high school graduation rates, and prepare youth for the workforce.

Healthy Parks Healthy People US is a National Park Service initiative that is a "holistic approach to promoting the health and well-being of people and the sustainability of the planet."

Barbara Butler Artist-Builder, Inc. was incorporated in 1999 to custom design, build, and install play structures. Barbara Butler combined play and art in her backyard play designs. Most of the play spaces fit one of four standard categories: playhouses, play forts, theaters, and outside structures for grownups.