DALLAS (CBSDFW.COM) – With every arm curl and every leg press, it seems Svend Muller of Dallas buys another year. “Got to keep my muscles going,” Svend explained after another arm curl at Gold’s Gym near White Rock Lake.

Muller hit the century mark Thursday and has no signs of slowing down. “I still go dancing. Saturday night, we’re going to a big dance,” said Svend.

At 100 years of age, he still goes to the gym twice a week. “I’m retired now, so what else do I have to do?”

Muller just might have his wife of 68 years to thank for his vitality. “We’re called Mr. and Mrs. Go-Go where we live,” explained Neva Muller with a smile.

The couple met when Svend was in the army during World War II. Neva, who is 11 years younger, told him that he was too old for her. But Svend had the perfect response. “Don’t worry, I will out live you.”  he told his wife-to-be.

Neva isn’t surprised that her husband still works out. In fact, she has a sneaky suspicion as to why. “Oh, it’s to flirt with the little white-haired ladies,” she said with a laugh.

Longevity must run in the Muller family. Svend’s twin brother passed away at age 98. So it’s no wonder why the birthday boy feels good about his future. “I feel good and I have hair,” joked Muller.

Which is more than many of us can say.