Engagement is a constant struggle when teaching high school. It varies so much from student to student and class to class. I agree that making the information applicable and relevant to students helps. Forming relationships with students also helps a lot. The saying goes, "They don't care how much you know until they know how much you care."
One of my biggest struggles teaching high school is helping students develop self-regulation. I think this is a big part of engagement. When students can successfully self-regulate, they can control their engagement even in activities and learning that doesn't interest them. We all have to do tasks, not because we enjoy them but because they just need to get done (who likes filing their taxes?).
