For the few times that I have tracked myself doing various activities, I have found that I didn't even need to do anything with the data, I was actively changing habits whilst I knew I was being monitored. For example, I wore a GCM for a few weeks and I found it difficult to live my "normal" day to day lifestyle. I wanted to do the things I felt were "right" and "healthy". Whether or not that is a good thing or not is a different topic, but just my 2c.