So there is this temptation to view each of our selves as these engines, which all function slightly differently, depending on the inputs of the environment and how we react to the inputs.
For example, one person might be floored by going out and being social, and so their energy is piqued and their entire experience of life is heightened. Others prefer quieter or at least more intimate environments with a different set of inputs. Or both of these situations can have different effects on different individuals based on moods at that moment.
It becomes advantageous to learn how one's own engine functions based on a very complex interrelation of inputs, outputs, and internal states, and to learn when to pursue a certain course based on one's own mood or disposition.
And then one should also take care into not falling into the trap of putting too much weight on a metaphor for understanding reality that is itself a mere instantiation such as understanding something as complex as an individual as a mechanical engine.
