The moral rules governing our lives can feel consistently real even though they cannot be explained by the laws of physics.
Taking drugs to make yourself happy. Having sex without an intended relationship. A lot of other 'bad' decisions, from the metaphysical point of view, have very predictable real world results by stealing happiness from our lives.
Why do most of us refuse to surrender these facts to the world outside materialistic understanding?
We can definitely make a case for a materialistic explanation for what you are describing by thinking about entropy.
Classic philosphers held happiness to stem from the state of Ataraxia, a state of equilibrium and equanimity free from distress and worry. This state is difficult to attain and easy to fall from.
Simply put, there are much more ways to be unhealthy, hurt or unhappy than ways to be happy, fit and healthy. Many more configurations of the physical system that is you can be deemed undesirable or "unhappy" (injury, sickness, hunger, confusion, mental illness, social alienation, worry...) than there are who are desirable or "happy". Therefore statistically, if we don't put some work in the system from time to time it will most probably decay into one of the many undesirable states.
Just like houses fall in disrepair if left unkept, if we don't eat we get hungry, if we don't exercice we get unfit, if we don't take care about hygiene we get sick, if we don't contact our friends from time to time they drift appart, and if we contact them in one of the many innapropriate manners they run away, if we don't prepare carefuly for the future we are left vulnerable and open to worry. It's easy to cut one's limbs, it's practically impossible to put them back in place.
None of that requires some metaphysical moral drive to push us to work. Living, social beings are complex systems and complex systems require work to be kept together.
Seeing the poem in your answer (now deleted), I have a feeling you will relate to Gurdjieff.
Here is an excerpt from "In search of the miraculous" — copied from here.
There is an Eastern tale that speaks about a very rich magician who had a great many sheep. But at the same time this magician was very mean. He did not want to hire shepherds, nor did he want to erect a fence about the pasture where the sheep were grazing. The sheep consequently often wandered into the forest, fell into ravines and so on, and above all, they ran away, for they knew that the magician wanted their flesh and their skins, and this they did not like.
At last the magician found a remedy. He hypnotized his sheep and suggested to them, first of all, that they were immortal and that no harm was being done to them when they were skinned; that on the contrary, it would be very good for them and even pleasant; secondly he suggested that the magician was a good master who loved his flock so much that he was ready to do anything in the world for them; and in the third place, he suggested that if anything at all were going to happen to them, it was not going to happen just then, at any rate not that day, and therefore they had no need to think about it. Further, the magician suggested to his sheep that they were not sheep at all; to some of them he suggested that they were lions, to some that they were eagles, to some that they were men, to others that they were magicians.
After this all his cares and worries about the sheep came to an end. They never ran away again, but quietly awaited the time when the magician would require their flesh and skins.
