I want to say that all actions can be reduced to a single motivation: trying to increase one's own distance from nonexistence. This definitely should be defined in negative terms. And altruism has been taken care of. (Long term self interest and empathy=understanding+occasional transference of suffering and the two levels of "morality" where we the simplistic level is just feeling pride for doing the right thing even when it clearly doesn't make any sense at all in a given situation.)
I want to say that everything comes down to a short term and/or long term thinking which gives the perception that the distance from nonexistence has been increased.
A potential road block is defining actions as instinctual; which is to say that no real "thinking" is going on. Such would mean that the motivation for some given actions (a pandora's box really of actions) doesn't come back to trying to increase the distance from nonexistence. It is instead just mindless. Stimuli A is received. Chemical is produced. Which in turn just causes action B as if it were just a mindless reflex.
To the extent it is true that actions are mindless/instinctual, to the extent our understanding of actions amounts to vague hand waving and the claim that it's just instincts, it would seem to be a waste of time attempting to understand humankind.
And there are actions that are outside of our control. Actions that I suppose amount to instinctual actions. Jerking one's hand back from extreme heat for example. To a lesser extent the beating of our hearts, the working of our digestive systems.
But where then is the line? I would like to think that except for things such as that, all can be explained as conscious/subconscious attempts at increasing our distance from nonexistence.
The point being that in explaining our actions, any person explaining their actions, instead of just saying, "I just do." Or for that matter explaining any complex series of actions by any person or animal as "instincts" I would want to see them be able to bring every action back to that one single assertion. We act, we bother to do anything in an attempt to increase our distance from nonexistence.
What little that can definitely be described as instinctual also generally increases our distance from nonexistence. But I find it somehow really a problem that there's not sense to it, that it's just mindless crap. It matters to me because I need to understand why I'm doing any given thing. And being told, "because I said so" or "it's your instincts"... No, that isn't going to work. I need to understand. I'm not a machine. Yes, I do jerk back from extreme heat. Yes my heart speeds up here and there. I remember once my hair even stood on end. But these are just little silly things. For any complex action, I can understand exactly what is going on and control my actions. I can understand exactly the process, exactly why I've the perception that the action will lead to increasing my distance from nonexistence.
When I ask someone to explain the reason for their actions, this is what I would most desire; something that always comes back to this one single assertion, that of an organism attempting to continue existing.
Saying it's just instincts, saying that's just what I do, saying there really isn't any reason = no good.
To understand everything you must be able to reduce everything to this single motivation.
A big road block is sex. I vaguely recall an answer from long ago which I've forgotten. But maybe not. Maybe with this everything collapses. Maybe we are permanently destined to be freakish creatures that get up, move around, and live for decades with not a clue why really we're doing much of anything.