Like many have mentioned, I play only when I feel the need to play. I don't play the sims habitually, so when I do play, it's because I am at that point of "awww, I miss my sims and REALLY want to play" I remember with Sims 2/3, I was what you would call seriously addicted sims addict and I played everyday, and every free moment outside of family life/work/adult reality, you could find me playing the sims. I never grew tired/bored of the sims. With sims 4, there's not enough to hold my attention for long periods of time, and yet there is enough there, coupled with my love for the sims, that enables me to actually enjoy playing the sims, whenever I do play the sims. Plus, I am such a slow player that I still have not attempted so much of this game. Seriously, a week for my sims is like a day for my daughter's sims. So there is still lots for me to do yet. For instance, I have never taken a sim family on a vacation in Outdoors Retreat. I've only been to the Flea market festival, I have never played even one of the GTW careers (I have played the city life careers), I have had very little actual club play, even though I basically set them up for much of my sims worlds. I'm sure there is more that I can add to this list. So, I haven't totally exhausted game play yet.
I suggest that you try playing the sims only when you really feel like playing, and only for as long as you feel like playing. Leave the game behind, and then allow that "I miss the sims" yearning to return, however long that may take.