Walt Roberson is, as he puts it, “an ol’ drill sergeant” and a Vietnam vet who spent more than 30 years working his beat as an Asheville police officer. He’s used to being tough, and at more than 6 feet tall, he’s probably never been a small man. But now 60, the retired city resident says he came close to “doing something stupid” after he left the force: He gained weight till he was pushing 400 pounds, had knee surgery, was diagnosed with Type 2 diabetes and got so depressed that suicide wasn’t much too close in his mind.