How productive have the last few days been for you? 

What information would you use to evaluate that?

How does your evaluation affect how you FEEL about yourself as a person?

It is highly likely that the rating you gave yourself on the productivity scale correlates to how you feel about yourself. The more productive you feel, the more likely you are to feel that you are effective and awesome at what you do. The lower the rating the more likely you are to feel that you are lazy and possibly even useless. No one enjoys feeling that they have "wasted" a day.

To be productive you have to have a clear, unambiguous goal to work towards. 

In other words, how you have just rated yourself, is dependent on the goal you had in mind as you were rating yourself. The more progress you have made towards that goal in the time you allocated to the job, the higher the rating.

In Dan Pink's classic book Drive: The Surprising Truth About What Motivates Us, he identifies three core, generic motivation drivers in all people:

1. Autonomy - Our desire to be self directed
2. Mastery - The urge to get better skills
3. Purpose - The desire to do something that has meaning and is important

All three require progress. 

Every single person wants to feel that they have progressed, every single day. In essence progress is what gives us relevance and meaning. It is the key to sanity and self worth.