Hey Reader, A few years ago, I was preparing for my first triathlon.To do it right, I did a Leistungsdiagnostik—a detailed performance test. The coach looked at my data: heart rate, pace, how my body produced energy.He said, “Sven, if you want to accelerate… you need to train slower.” Slower? That made no sense. But he was experienced—so I listened.He set my max heart rate to 130.Too fast? Stop. Breathe. Slow down. And over the next year, something amazing happened:My pace improved—over a...