So many of the ones pp have said are true for me but I haven't done them forever!
Swimming in the sea surrounded by mountains with DH.
The constant glimpses of the mountains and the ocean and the palm trees as i went about my day, when we lived in coastal LA.
A short but intense workout (afterwards).
When the kids are both in school for a whole day with no illness, school closures, late drop off or early pickup required and I can actually Get Something Done for a change.
Finishing something I have been working on (either at work or in the house, a tidy room or big pile of sorted laundry will do!)
A glass or three of wine and a nice meal on a terrace with a view.
A real log fire in the evening, especially at the end of a day's hiking.
Playing on the computer with DH after the kids are in bed.
Cuddles with the kids when they're being nice.
When DS (6) tidies his room (very rare).
Hanging out with my friends on a girls night, before I moved city and stopped having any.
Being slim (thank you Andrew jenkinson)