The purpose of the quantified self idea is not to quantify everything we do. Instead, it is to develop awareness and make better decisions.
Thanks to Technori.com for the image
The hypothesis with quantifying the number of steps we walk, for example, is that we will develop a sense of the amount of movement we need in a day and design our life accordingly. For example, you might realize that a normal work day doesn’t cut it and that you need to schedule at least one walking meeting every day.
Of course, there is something visceral about being presented with numbers. As humans, we feel the need to optimize it and often do so at the expense of other harder-to-quantify parts of our life. The salary is a perfect illustration of this obsession.
The future of the quantified self movement is likely a smart chip that is embedded within us which would provide us a daily read of all our vitals. Again, it isn’t the numbers that will matter but the decision about what to do with them. So, chips will presumably be smart enough to guide us to take appropriate action.
The purpose of most numbers in our personal life is to get to a point of awareness of our behavior. Ideally, budgeting becomes a 5 minute exercise every week because we trust ourselves to make the right calls. It follows, and this is the counter intuitive idea, that the purpose of quantification is to stop quantification.
As always, the numbers are what they are. What matters is what we do with them.
A Learning a Day 
