This is kind of why I like fitness trackers (minus intrusive user tracking) and would like to see them ever expand into automated tracking of users' physiology, allong with simple seemless logging of experience (like hitting a button to log a headache, or some other minor symptom that might be nothing but months or years of trends might reveal an issue)

It reminds me of the problem of a car noise, but you bring it to a mechanic and it doesn't reproduce on the spot so diagnosis is extremely hard. In fact I've had a heart issue of this sort recently where I experience symptom intermittently, sometimes weeks or months apart. My cardiologist has brought me in multiple times for an EKG, but since itt not while I'm having the symptoms we have no idea if the normal EKG readings are telling an accurate story.

Essentially I want to see personal health devices like the black-box on an airplane. Take blood pressure, weight, and resting heart rate once a week? It goes to the black box. Log a physical symptom or mood? Goes to black box. Sleep and activity patterns, I integrated smart-watch EKG? Goes to black box.

I think the advent of truly seemless UI and UX with unobtrusive comfortable devices that could do this would provide a massive leap forward in preventative health.

We just need to get there in a way that doesn't make it one of the most massive land-grabs ever of personal data by device vendors.