Riding a sailboat hard on the wind, watching the foam of the waves splatter onto the deck...

Reading a book in a comfy chair, only accompanied by the sounds of a fire...

Learning something new that changes your worldview completely...

Cooking together with your partner...

Watching your children grow...

"Fun"... "fun" is short lived like the buzz you get from a glass of good whiskey, i would say its better to strive for happieness

Fun can be many things, and it's definitely not constrained to being "productive".

What does being productive even mean to you?

If you do everything productivity porn tells you to do, you probably won't be "successful" anyway, and you'll live an empty, Patrick Batesman life.