How Do You Have Fun in The Sims 4?

You can't force yourself to like a play style. I like to stick to certain main characters and play with aging off. I have many save games with different story lines and themes. Sometimes one save game calls to me if that makes sense and I play with it for awhile. I like to build their worlds and add secondary characters... So I might build a save game based on a favorite movie (ect), research the characters and make them and then just go in and give them a life of their own. If I can find their homes or hangouts on the gallery I might add those in... or find a build that's close enough and try to convert it. I try to play them somewhere between what their real story is, what I want them to do and basically allow that it's going to be a parody. So a horror story is more like a black comedy. A sitcom cast .. well they fit in pretty good. If I get meh about it I rotate actually nearly every time I sit down to open the game I think who do I want to play with today? Except for those days I'm just absolutely driven to play a certain way. Sometimes it's the same sim for a very long time, sometimes they get a day or a few hours.
Then I make my own stories or easy challenges. When I'm feeling bored, or don't know what to do, or even just not feeling creative enough to tell a story I go directly to deviant play and a lot of NPC, and townies give their life or start reproducing like crazy.. or a mixture of both.
I don't worry about it or feel I'm playing it wrong. Just find what entertains me day by day.
When I don't feel like playing the sims .. I don't.