Amari Mow hit the ground running the moment he arrived in Lexington. Massachusetts. And no matter the obstacles he’s faced, he’s been a positive presence. He’s an incredible leader, and all of his hard work is paying off. “I started in Boston and then, like, I moved to Lexington my sophomore year,” Amari said. A Roxbury native who entered the METCO program in first grade, Amari is now an 18-year-old senior at Lexington High School. And it’s been…