There are two different measures you can rely on to determine productivity. When combined, they yield the best estimate of value generated for the effort you put in. The first and most important measure is how you feel about the work. Is it satisfying? Is it meaningful? Is the work aligned with your beliefs and goal? A recurring thread in my writing, the passion we have for our work is the essential ingredient to creating real value.
The second well known measure is how much wealth or social value is generated by your work. Many get rich by means other than creating social wealth, but they are the exception. For the greater part, the largest earners have done the most to benefit society. As we iterate on the function of wealth, those who game the system will diminish, and those who create real lasting value will be more richly rewarded.
Take for example the creation of Avatar by James Cameron. It is a masterpiece of 3D virtual crafting, and I fell head over heels in love with the world of Pandora. Mr. Cameron had achieved enough wealth that he never needed to work again after blockbuster successes with the Terminator movies, and Titanic (among others). Avatar was the result of a truly liberated crafting. It is driven primarily by his own need to share a story and a world that has haunted James' (and his visual designer's) imagination for so long. His efforts to manifest this film extend 14 years of writing, planning, designing, creating, and organizing a magnificently gifted production group. The source of the dream for Avatar, is what has driven James forward through a life of groovy film making. By my count, both measures of value are off the scale. Thanks Mr. Cameron and all who shared your vision.