Comment:

Many major religions and philosophies will have, as a selling point, the idea that following their precepts is the way to a happy and healthy life.

Of course, then, you have to contend with the human brain, which frequently will feel bad for reasons that do not correspond to ethical rightness or proper lifestyle. You have to contend with people willingly taking on difficult or painful realities as a form of sacrifice that is clearly laudable, good people compelled to be miserable because of their goodness. You have to contend with bad things happening to good people.

I remember, as a young Christian boy, being taught that Joy was one of the Fruits of the Spirit, and singing "I've got the Joy, Joy, Joy, Joy, down in my heart", followed immediately by a clarification that "joy" was not, necessarily, the same thing as feeling happy all the time, or even necessarily feeling happy ever. "Joy", you see, is simply acknowledging that God is Good and the sacrifice of Jesus on the Cross is Good. I guess. (One must wonder what "joy" will await believers in heaven.)

Anyway, if someone says "do this and you'll be happy all the time", they're either a con artist, a cult leader, or a drug dealer. Maybe being a good person and doing the right thing isn't about that.