All summer, Kristaps Porzingis worked on getting stronger. He lifted weights. Ran. Did boxing. He wanted to evolve into what Pistons coach and executive Stan Van Gundy recently predicted for him. “He’s going to be a nightmare for years to come in this league,” Van Gundy said. So far this season, opponents are losing lots of sleep over the Knicks’ 7-3 Latvian. Next, it’s Houston’s turn to combat him, Wednesday at the Garden. “Some of the stuff he does,” center Enes Kanter said, “we just look at each other on the bench like, ‘Man, did he really just do that?’” Like going up nearly into the rafters to flush an offensive rebound. Or draining a 3-point shot seemingly from Times Square. Porzingis, 22, has evolved frighteningly fast in his third season. Porzingis is growing, literally and figuratively. Monday, he demolished Denver with 38 points, scoring inside and outside. At his size, he simply shoots over everyone, although the Statue of Liberty might present problems. But he’d probably just drive around what Knicks fans consider France’s second best gift to America — right behind Frank Ntilikina. “The biggest thing is him getting stronger, then him understanding his spots on the floor and where we got to get him the ball,” said Courtney Lee. “Anywhere between 15-to-10 feet on the floor, that’s his money area. He wants to get the ball right there. There’s nothing you could do once he puts it above his head to shoot it. So it’s him getting stronger and being able to get that position then us just being able to execute and get it to him at the right time.”