It is no surprise that so many people are so unhappy when so many prefer irrational reactions to intentional rationality. Automatic, emotional reactions are guaranteed to limit a person to much less joy than they would otherwise have.
Decisions that optimize for long-term joy require thinking. Only through thinking can you discover, enumerate, and select what is best. While feelings are automatic, thinking is not. What little thinking occurs today seems mostly occupied with composing post-hoc reasons to justify decisions already made emotionally.
Reason is required to maximize the quality and duration of feelings. Prioritizing reason over feelings does not kill them; it makes them stronger, more enduring, and deeper.
Joy is not merely a sensation of the flesh, but a physical sensation coupled to and at least amplified (but sometimes wholly caused) by thought. Joy is the fusion of sensation with reason. The fulfillment of the potential of both sources is required to maximize the composite. To think of or experience joy only in terms of a physical sensation or solely as a product of the mind is to rob it of its richness.
If you seek to maximize your joy, you must increase your reasons for having it. You must understand the relationship between feelings and value. Feelings are the conduit through which you sense value. Feelings do not produce value—they flow from it and endure because of it. Value is maximized by reason, not feelings.