Serotonin is a neurotransmitter that plays a role in mood. It is important for reducing depression and regulating anxiety. It also regulates digestion, sleep, and bone health.

The hormone dopamine is related to motivation and reward. It's why you feel good to reach a goal or lack interest when you have low dopamine.

Endorphines are linked with exercise. They function as natural painkillers that help minimize pain and maximize pleasure, explaining why an athlete may be able to push through a race with an injury that they don't notice until later.

There are four main hormones that trigger the feelings of happiness: dopamine, serotonin, oxytocin, and endorphins.