Accidentally overhearing someone say something nice about you.
Waking up and realizing you still have a few hours left to sleep.
Your first kiss (either the very first or with a new partner).
Making new friends or spending time with old ones.
Playing with a new puppy.
Having someone play with your hair.
Road trips with friends.
Swinging on swings.
Making eye contact with a cute stranger.
Making chocolate chip cookies.
Having your friends send you homemade cookies.
Holding hands with someone you care about.
Running into an old friend and realizing that some things (good or bad) never change.
Watching the expression on someone's face as they open a much desired present from you.
Watching the sunrise.
Getting out of bed every morning and being grateful for another beautiful day.
Knowing that somebody misses you.
Getting a hug from someone you care about deeply.
Knowing you've done the right thing, no matter what other people think.