Recently I´ve grown interested in the whole Quantified Self thing. It has many other names, but the core meaning is clear: We, humans, are beginning to have better and better ways to measure ourselves.  This capability increases along 3 axes:
- Measuring ourselves is getting cheaper (e.g. measure your heart rate with a phone App)
- We can measure much more stuff (e.g. heart rate, physical activity or blood sugar levels were just the beginning, now we can get readings on hemoglobin saturation, ECG, HRV and PWTT all in 10 seconds, with a single device)
- We can measure our bodies with increasing precision at levels that used to be reserved for scientists, astronauts or doctors.
More on this later on. 
Traditionally speaking, doctors help people by identifying causes for problems and, based on their extensive (and expensive, but more on that later) knowledge, suggest strategies and treatments. While a lot of symptoms require nothing more than a visit to a doctor to be detected and/or identified, others need some more advanced diagnostic procedures and tools. But these are getting easier to get a hold of.