These kids (only one of whom is mine) were not exactly working out. They were enthusiastically marking an unexpected turn in my youngest son’s tenth birthday party, as he and his classmates commandeered our open-air gym for play.
A workout area that my older sons trained on for lifeguarding and military fitness testing had become an imaginary volcano or pirate ship. This scene fit our backyard’s evolution: A gym we planned as a repurposing of firewood storage has become, on its own, something akin to a neighbourhood park. Along the way, my children have used the space to develop agility, stamina, and strength.
It all began in 2015, when my teenaged sons and I sketched out a design for three firewood racks. With pressure-treated lumber, power tools, and plenty of labor, we began building on New Year’s Day 2016. After two weekends, we had a trio of racks that together could hold six cords of wood while also doubling as an alternative to a dingy basement gym.
To one rack we added a high wall for wallballs. To another we fastened a pullup bar. For the third, we designed an angled beam rising about 16 feet in the air, from which we suspended the climbing rope. To this rack we also affixed a crossbeam, and from it hung a TRX set and a pair of rings.
By spring, we had stocked the rack with firewood and the gym with an Olympic bar, a set of plates, and kettlebells. Through a friend at her CrossFit gym, my wife found a free tractor tire.
The gym was not perfect. The weight of the firewood and the softness of the soil caused the centre rack to sink unevenly, a tic that remained even after we jacked up and braced the most offending corner.
With time we came to accept the flaw, just as I accept my own limits and the joint pain that has come with advancing age. Friends teased us playfully. Some called the space a prison gym. Others asked if I came up with the idea on a combat outpost in Afghanistan, where I had previously worked.
This latter question was fair. American troops in remote positions concoct novel ways to work out in confined spaces and under the open sky, often with makeshift equipment, including dumbbells made from packed sandbags and tent poles for pullup bars.
My sons and I did not draw directly from any of those many designs. But war-zone gyms had proved to be both practical and fun, and demonstrated something too many big-box gyms miss: simplicity. They provided conceptual inspiration.
Remember that word. Fun. Whatever the merits of this firewood-rack-and outdoor-gym combination, once built, it needed no sales pitch. The gym attracted uses on its own. My oldest son, Jack, was a lifeguard at a state beach in the summers after his high school junior and senior years. Between shifts, he conditioned at the gym; we would see him shirtless, swatting mosquitoes as he put himself through wallball and kettlebell circuits, and mastered rope climbs without legs.
My next oldest, Mick, is a high school senior with plans of joining the Marines. Often I see him on the rope or at the pullup bar, headset on, in the zone.
These scenes were predictable. What we did not anticipate was that our gym would become a gathering place, too. Joe, now ten, was six when the gym appeared in his backyard. My daughter, Elizabeth, was 11. Both of them took to the gym as if it were a playground, and their friends joined them.
In the summer, it’s a fortress to be defended or stormed in a water-balloon war. In the winter, the ammunition changes to snowballs. Sometimes I look out the window and see children from up and down the street clustered around the tractor tire or rope, engaged in games they have invented, complete with rules only they know.
We built the centrepiece for all this training and play for less than the annual membership cost at the local fitness centres. Almost five years on, it’s hard to imagine money better spent.
This article originally appeared on Men's Health