Endorphins are released for the body to be able to sleep. Exercise helps release, dopamine, endocannabinoids and more, which prop up the mood of the person. Endomorphins or endorphins are released for exact the same reason, doctors used always morphine, to numb down the pain of damage to the body from the excersise, or a surgical operation, or a bullet, and the patient is able to sleep.

For me happiness for this year is learning Rust.