Tunaisafish has a package of mods titled
Enthusiasm Overhaul to address the following:
1. Sensible handling of interests and hobbies to be more in line with the Sims' personalities
2. Slow enthusiasm decay depending on the number of hobby points
3. Phone calls are handled differently: no phone calls
I use that package of mods myself and liked how my Sims can focus on their true hobbies and not do random activities to hobbies they have no interest in.