6. Skill Points
Sims are not lazy creatures. They are big into self improvement. Or at the least, you can force them into self improvement. Many versions of the Sims require a certain level of a certain skill to be promoted in their job. There are objects you can purchase to heighten your skill levels. In Bustin' Out, I use the Cheat Gnome to fulfil all motives and then force my Sims into major skill building - for example, working out all night to get body points, playing interminable games of chess for logic points, reading books all around the clock in order to improve their cooking and mechanical skills. In fact, in my latest game, I have maxed out all of my skills so early on in the game, I have nothing left to do!