Lets say that my end is the safety and comfort of my family. There are various means to that end, but not all of them can be justified. Whether or not they can be depends on personal and social norms and values. Closer to the core are my own ethics which define what I am willing or not willing to do to meet that end.
Not necessarily true. Some people have varying degrees of altruism as it applies to work. I for one have a very strong psychological need to produce. Given a task to do or the option to pass on it, I will take a task every time, and occasionally just make shit up for the sake of doing something, rather than just sit idle.
Which does not account for obsessive compulsion, or the inability to realize when enough is actually enough. Some people, given the opportunity, will work themselves literally to death.
Then how does generational wealth occur, like Gates, Mellon, Carnegie or Rockefeller sized estates? Those guys were responsible for more production in one lifetime than even the most lavish or opulent of lifestyles could consume. Not only their own, but all that derived a living in their employment.
I think I get what you are trying to define, but what you are trying to define is somewhat polyhedral in the scope of human nature. It would have to encompass everybody from a socially defunct do nothing, which no amount of reward or suffering can motivate, to apex producers who literally change the world when their ideas become actions.
Thats a lot of ground to cover.