In prison, a guy asked me to help him calculate how rich he’d be once he got out. We ran the numbers. Perfect assumptions. Perfect returns. I slid the paper back and said, “Your calculator works. Your habits don’t.” He looked confused. “Math doesn’t fail people,” I said. “People fail math.” He stopped asking about returns. Started asking about discipline. Lesson: The math is easy. The behavior is brutal. That’s why so few win.