Katherine Kersten: In free time, do you fritter or fulfill?

On a typical evening we flop down, flip on the 36-inch flat screen, click the mouse, text, tweet, or feast on Facebook. The more adventurous among us grab virtual swords and enter the explosion-filled, fantasy universe of games like World of Warcraft, where we achieve instant superhero status.

We're megaconsumers of passive entertainment, spoon-fed by faceless folks in Hollywood or at companies like Sony. It's fun. It's relaxing. But when we log off, we often have a nagging question: Have we just wasted a lot of time?

It's a good bet Ingemar Holm never asks himself that question. Holm, 73, of Delano, is retired. The perfect time to enjoy passive entertainment, you say? Not Holm. He's got something that sounds long-ago and far-away: what we used to call a "hobby."

Holm's hobby is restoring vintage aircraft. He and his buddy Jim Johns, 75, of Bloomington have restored 18 World War II airplanes. Their latest project -- in which Dale Johnson, 73, of Burnsville and a dedicated band of three or four others have joined -- is the painstaking restoration of a World War II CG-4 combat glider.

The CG-4 was a giant, engineless aircraft -- a fragile contraption of wood and canvas that was towed at night behind cargo planes and released for what were often clandestine, behind-the-lines missions. Between 1942 and 1944, about 4,000 Twin Citians labored around the clock to turn out these "flying coffins," making 1,500 of the 14,000 produced nationwide.

The CG-4 glider was the only military aircraft ever made in Minnesota, according to Johns. Today, only seven remain in the world, most in woeful disrepair.

There's not a screen, a mouse or a game controller to be seen in the Eagan workshop where the glider is slowly coming to life. Instead of offering nonstop "fun," the project, begun in 2007, requires careful planning and slow, steady attention to detail.

To build an aircraft like this requires thousands of man-hours, as well as the ability to delay gratification until the great day when the glider -- now 80 percent finished -- is complete. How did Holm, Johns and Johnson develop the abilities and character traits necessary to do this?

As boys, they were all captivated by the wonder of flight. Johnson credits his childhood on a farm in Bathgate, N.D., with firing his imagination and teaching him to stick to a task. "If you wanted a toy, you had to make one," he says. He pounded his first airplane together out of old barn boards.

As a boy, Holm used to hang around a giant pile of wooden discards at the old Tonka Toy factory in Mound. "We'd find busted wheels, and take them home to build our own cars, trucks and planes from the rejects," he recalls. Johns, for his part, remembers lovingly constructing model airplanes out of cardboard, because wood was hard to come by. "You'd spend hours cutting out and gluing the 1/16th-inch layers, and then sand them down into just the right shape."

What differentiates these men's hobby -- inspired by childhood games and projects -- from our electronic playland? Unlike our frenetic digital amusements, their use of leisure time requires patience, resourcefulness, self-discipline and perseverance.

It also hones valuable, real-life skills -- in their case, in design and wood and metal working. With these skills, they can create something tangible, instead of getting caught up in will-o-the-wisp superman clicks that evaporate each night into the ethernet. Rather than offering an escape from life, their hobby is life-enhancing.

In 25 years, how many of us will be equipped to take on the kind of creative project these men are engaged in? When we get drawn into our passive, seductive electronic world, are we just indulging in a few hours of misspent leisure time, or is there something more at stake?