I've had an iPhone for many years and just recently discovered the Health app. My phone has a lot of my "steps", an estimate of my calories, data about my walk

I've had an iPhone for many years and just recently discovered the Health app. My phone has a lot of my "steps", an estimate of my calories, data about my walking stability, and tons of other stuff. You don't even need a watch to get +/- 65% accuracy on anything except heart rate.