Exercise boosts endorphins.
Physical contact boosts oxytocin.
Sex does both.
Chocolate helps produce serotonin.
Capsaicin-heavy foods will make your body produce adrenaline and endorphins.
Caffeine is a drug but can give you a long hit of dopamine โ but overdosing will make anxiety worse, and can fuck with your sleep cycle. It's also rapidly addictive and the withdrawal symptoms include malaise and depressive feelings.
A stable sleep cycle is A#1 for happiness, though. It won't make you happy on its own but screwing it up will make you unhappy on its own, so it's the foundation to build everything else on.