I'm a runner, so diet is important. For 9 months I tracked everything I ate. Weighed portions, counted calories, logged everything. The data was insightful. I learned that I need to eat 3,300 calories a day to maintain my weight, with a range of +/- 300 calories.
After 9 months I stopped tracking things because it became time-consuming. Partly was because I learned what it "felt" like to be full, but mostly because tracking it all was really annoying. If all of that could be automated somehow, I'd love to have a spreadsheet of data which I could graph and chart. "At 8:16am, you drank 7.8oz of Orange Juice, totalling 108 calories." Cool, my O.J. container and glass measured that automatically, and uploaded it to my database!
But right now doing it is extremely manual. All of Wolfram's amazing data comes from some sort of automated system he setup once and never worried about. A pedometer. A script chewing through 20 years of archived emails. That form of automation doesn't exist for many types of data people would like to collect, such as food intake, or blood sugar testing for diabetics.
Inventing these non-invasive automated sensors is key for society-wide personal data collecting. Otherwise most data gathering will be sentenced to the dedicated few, rather than the busy many.