Who knew dentists were so . . . studly? (WELL, OK, dentists probably did.) Gaze in awe at these two 40 Under 40 alumni who attack the outdoors with ferocity. And perhaps a forceps.

Dr. Casey Culberson

Fueled by nothing but the wind and pure joy — talk about renewable resources! — Dr. Casey Culberson and his brightly hued kiteboard find travel magazine–worthy adventure in a host of exotic locations.

“If you put your passion into something, you’ll reap the rewards,” says Dr. Culberson, 43, who practices at Mill Creek Family Dentistry in Mill Creek, Washington, just north of Seattle. “This is true in both dentistry and kiteboarding.”

About those exotic locations: “My favorite trip so far was Tahiti,” he says. “Kiting in the lagoons of Bora Bora with lemon sharks and stingrays below you in crystal-blue water, with mountains in front of you — absolutely breathtaking.”

Dr. Culberson is something of a Renaissance man, having won an Edison Award for his invention the Molar Media Mount, an arm that affixes to a dental light and positions an iPad or other tablet directly in the patient’s line of sight. But it’s the utterly low-key kiteboard — no motor, no nada — that most captivates him. Long a water-sports aficionado, he has a sailing background. “I saw some people kiteboarding once, and it looked so magical that I said, ‘I will learn to do that!’ ” Dr. Culberson says.

And so he has. Yet even this now-skilled kiteboarder, ever in pursuit of a challenge, has reveled in his recent return to newbie status. “The new thing in kiteboarding is hydrofoiling,” he says — in which one’s board has a metal mast extending 36 inches from its bottom; as speed increases, the wing creates lift and the board ascends. “With almost no drag, you silently hover above the water,” he says. “It’s an experience like no other.”

Among his treasured spots: Turks & Caicos, the Baja Peninsula and of course his own Pacific Northwest. Wherever he goes, though, he finds that this work-hard, play-hard pursuit is attractive to . . . a certain kind of medical professional. “If someone on the beach asks you what you do, and you say you’re a dentist, they’ll usually say ‘another dentist kiteboarder?’ This sport, it seems, really appeals to dentists.”

Dr. Jesse L. Jackson

It’s never too late to make a change. Take it from one engineer-turned-dentist who has made transformation his life’s blueprint.

Today, Dr. Jesse L. Jackson leads two successful dental practices in the Kansas City, Missouri, area. Fifteen years ago, as a newly married mechanical engineer, he never envisioned himself in the profession that suits him so well today. Yet his wife — who was in hygiene school when they met — encouraged him to shadow her. “I fell in love with the dental field,” he says.

Transformation guides his personal life as well. “I was an overweight, non-athletic adolescent,” Dr. Jackson, 37, says. “I started running. Then I started working hard at sports. Pretty soon I was no longer the last to be picked on teams.” It only stands to reason, then, that this man who didn’t grow up around boats or lakes would take to wakeboarding like a fish to . . . well, you know.

He has been on the continuum of wakeboarding’s steep learning curve since 2013. The sport differs from kiteboarding in that a wakeboarder has no sail and stays mostly in the water, using his full body to battle the waves. “I’m still honing my skills and trying new tricks,” Dr. Jackson says. “I spend each summer learning new moves and staying fit.”

His four biggest fans? His children, ages 5 through 10, all of whom have taken up the sport in the wake, as it were, of their dad doing the same. “It’s been super-rewarding,” he says. “It gives me a chance to show my kids they can do anything they want as long as they prepare and work hard.”

A favorite family trip: Table Rock Lake in the Missouri Ozarks. “The water conditions are perfect, the scenery is beautiful and the amenities are second to none. It’s the most relaxing place on earth for families,” Dr. Jackson says. Well, relaxing when you want it to be: Much of the time you can find him there executing maneuvers such as a switch 180 heel-side, stalled 360, toe-side grind and wake-to-wake jump. And so Dr. Jackson’s transformation continues. “Most adults won’t try to learn new things, or think they’re too old to do things like this,” he says. “Since I didn’t have the opportunity for many things in life when I was young, I figure now is the time to try.”