Happiness is a surge of dopamine, serotonin, oxytocin or endorphin. These brain chemicals evolved to do a job, not to surge all the time. When you know the job they do in earlier animals, you can make peace with your inner mammal. You can wire yourself to enjoy more happy chemicals and relieve more unhappy chemicals. Your old wiring was built by accidents of experience in your youth. It will shape your ups and downs until you build a new place for your electricity to flow. It's not easy being a mammal, but we’re lucky to live in a time when our operating system is increasingly well understood.