If we examine a person, we will notice that he performs his daily actions as a must. He has no choice about them, because both our inner and outer nature affect us through the two forces: pleasure and pain. Anyone who perceives this impact on him, feels denied of free choice, because in no way that person can freely choose pain or reject pleasure. Thus, the essence of our nature is the desire to enjoy. That is why if we do make a choice, it is always aimed at attaining maximum pleasure at minimum effort. Let us assume that I don’t really want to go to work in the morning, I come home tired in the evening, but at least I know that I can provide for my family. I make a simple calculation, that I have to be in pain all day long, in order to survive and the bottom line is that I replace the pain – my efforts – with what I need in order to survive.
But in any case, each body that exists in this world makes that calculation, because he feels his life as a series of receiving pleasures or escaping pains, and he lives only by the calculation of pain and pleasure and has no determined plan of conduct. Each of us has his own character, birth attributes, values and concepts we have acquired during life, our upbringing and our senses, social pressure, individuality etc. That creates in us a system, a mechanism by which we act and calculate.