If you didnt know better, you might make the mistake of calling Glenn Sperry old.His thick glasses sit evenly below his gray head of hair. Even Sperrys faded green swimming trunks seem to be a relic, abruptly ending closer to his waist than knees. But ask his friends or neighbors, and Sperry is anything but old. Thats because theyve seen the 72-year-old glide across Lake Worth on water skis like a man who is 27. In fact, skiing on an actual pair of water skis is simply Sperrys warm-up act. For more of a challenge, he might surf across Lake Worth on a wooden saucer 3 feet in diameter. Or he might float perched atop 6-foot stilts, as if he were a circus performer moving not on land but on water.If its got a flat surface, Ive skied on it, said Sperry, of Fort Worth.On this particular day, Sperrys trick involved the wooden saucer and a folding chair. While balancing on the saucer behind the boat, Sperry carefully unfolded the metal chair previously tucked under his left arm. Then, like an Olympic gymnast, he pushed himself into a handstand on the chair, his toes pointed toward the blue summer sky. He held the acrobatic pose for 10 seconds before returning to his feet.A bad day on the water for Glenn is the best day for any of us, said Chuck Reagan, Sperrys friend and so-called partner in crime. The narrow brick hallway leading from Sperrys front door to his living room is a miniature museum of Sperrys water-skiing career. Black-and-white photos of a younger Sperry performing tricks line the wall, eventually giving way to color photos. Most of Sperrys career is chronicled here, including his time as a member of the Tommy Bartlett Show, a water-skiing act customers still flock to see in Wisconsin Dells, Wis. The show, in its 61st season, features daredevil water-skiers performing acrobatic feats. Sperry used the money he earned there to fund his college education.That ones me on the 10-foot stilts, Sperry said, pointing to a dusty black-and-white photograph. Im the only person in the world to do that.On the opposite side of the hallway are some of Sperrys 400 trophies, neatly arranged across four shelves. Lost among the army of miniature gold men are Sperrys two National Championship awards. Ones from 1957, the other 2007. Sperry is the only man to win the competition 50 years apart, and the margin isnt close. For as long as he can remember, water skiing has been a part of Sperrys life. He took his first lesson as a 6-year-old in Baltimore. Richard, the Sperry family patriarch, taught all four of his children and was an accomplished water-skier himself. In the spring of 1952, the family moved to Fort Worth. The Sperrys brought with them their love of water skiing. Countless summer days were spent on Lake Worth, skiing until the sun set. A decade later, Sperry bought a house of his own overlooking Lake Worth, where he raised his four children with his wife, Judy. Though he didnt know it at the time, Sperry would never leave. He got a job teaching woodshop at Castleberry High School, and spent his summers skiing in shows all around the world. In 2006, just months after Sperry retired from teaching, Judy died. During that difficult time, Sperry turned to two of the things he loved most: water skiing and teaching. Quickly, Sperry realized the reward of teaching others what he had spent a lifetime doing.My greatest joy is seeing someone else stand up and water ski for the first time, Sperry said. Theres nothing like it.These days, Sperry is happily remarried. During the summer months, he skis between three and four times per week. Weather is rarely a deterrent.He goes out there in the winter with his wet suit on, Sperrys wife, Cynthia, said. It has to be real cold for him not to be out there.At 72, Sperry has hardly slowed down. After all, 72 in the Sperry family is young. Sperrys mother, Lucille, water skied until she was 100. Ill be 73 years old this year, Sperry said with a smile. I dont do some of the stuff I used to, but I can still do a lot.The way Sperry sees it, some of his best years are still ahead.