Talk with a positive person

Go for a walk

Laugh, even if you have to force it, the mere action of laughing releases endorphins

Buy something new (even something small, like a new type of coffee)

Breathe deeply for at least two minutes. Focus on your breaths

Cuddle (with a lover)

Take a small risk daily. Find something that makes you a little nervous, like talking to strangers, and strive to do it one time every day to build your confidence

Take up meditation (15 minutes a day)

Smile often