Things I do -

Dwell on fond memories, try to remember the best experiences of my life.
Get a hug, cuddle, foot rub, massage, etc.
Check if I took my vitamin D if there is no sunshine.
(But a couple times it's been so bad sunshine didn't touch it.)
Exercise very intensely for 20 mins.
Browse the public library for a book to escape into.
Re-watch favourite comedy movie.
Listen to intense songs - eventually I often end up singing alone, which is cathartic.
Listen to birdsong, even on the internet if necessary.