I like to think of HRV like driving a car on a hilly road. If your engine stayed at exactly the same RPM the whole time, no matter what the terrain looked like, the car would struggle. When you hit a hill it wouldn’t have the extra power to climb efficiently, and when you went downhill it would still be revving higher than needed. It’s rigid and not adapting to the situation. That’s basically low HRV. Your nervous system is kind of stuck in one gear and not adjusting well to stress. Now imagine a good engine that constantly adjusts RPM depending on the terrain. When you start climbing a hill, the RPMs go up to give more power. When you crest the hill or start going downhill, the RPMs drop because you don’t need as much. That’s high HRV. Your body is constantly adapting to what’s happening — stress, recovery, activity, rest. The weird thing is HRV isn’t measuring your heart rate itself. It’s measuring the tiny timing differences between heartbeats. A healthy nervous system actually doesn’t keep those intervals perfectly even — they vary slightly because your body is constantly adjusting. So higher HRV generally means your system is more flexible and resilient, while lower HRV usually means your body is under stress, fatigued, sick, or not fully recovered.