How are/were you behaving in this happy state? What is your physical state like? What are you doing? Saying, to yourself and others?
We all have things we do when we are happy. So a way to access that happy state when you are feeling less than that is to act it out. It’s pretty hard to stay feeling down when you are dancing around the room to your favourite song.
A few examples of happy behaviours might be:
Smile, a genuine smile
Laugh, a belly laugh
Count your blessings
Dance to your favourite song
Treat yourself to something
Tell a joke
Jump up and down
You may even like to create a reminder to smile more regularly, maybe a funny photo that pops up as a reminder on your phone/ your computer? A message stuck to the wall?