The intensity is fine with my original Apple Watch Ultra. I'm not sure the technique works, though. I mean, I feel the pulses quite a bit, and even in my phone, but I'm not exactly sure what I'm supposed to do. Am I supposed to speak on the beat, which is weird, or is it just supposed to distract my brain enough to not allow me any blocks. I've only completed one phone call with the app, so I don't have enough data points to know if this technique even works for me.