Might help to have a challenge or look for one where you can alter the rules to make them what you prefer, me though I like a story in mind or to make one with the character playing with cc. Mccc helps too as I usually let it mess with unplayed sims a few days of just basic simming with a family popping out kids then I may have things to choose from if nothing comes to mind. Lilsimsie and plumbella have save files and instructions for installing them with new sims and builds or makeovers I think Plumbella put more work into hers but just playing there and then having my own saves is fun aside from taking a break and thinking of stuff I might want to play out. If nothing works then maybe you just enjoy starting fresh a lot which is nice too just to use them for a little while before you move on.
One other thing have a save file set for long, and full seasons if you have seasons, then have another save for the middle setting and another save that is the shortest bounce between them and see if stories keep you going or just have a legacy. Set a goal for a sim week or two if you're still interested keep adding more time and when it's done it's done.