Aspiration (The Sims 2)

$$ Aspiration is the personality attribute that determines a Sim's wants and fears and possible motives in The Sims 2. Sims will have one of eight aspirations at any given time.

In the base game, once a Sim's aspiration was set - either at creation or when becoming a teen - it can't be changed. With University, Sims can change aspiration once after finishing their sophomore year. The second Expansion Pack Nightlife adds the ReNuYuSenso Orb, which in effect means a Sim can change their aspiration whenever they want. In the FreeTime EP your Sims can have a secondary aspiration.

Note: Babies have no aspiration.

The Sims 2

 * Grow Up: All toddlers and children have this aspiration, and it cannot be changed. Growing up involves learning essential life skills and (in the case of children) making friends and success at school.
 * Family: Family Sims will want to have children, and eventually grandchildren, and for those children to excel in their own lives.
 * Fortune: Fortune Sims want to earn money, gain promotions, marry a rich Sim, and put their income towards new household items.
 * Knowledge: Knowledge Sims want to gain skill points, and to eventually max out skills. They may even want to experience the abnormal, such as ghosts or alien abduction.
 * Popularity (sometimes referred to as Reputation): Popularity Sims most of all want to accumulate friends and best friends. Parties are also craved by these Sims.
 * Romance: Romance Sims want to engage in casual romance, and particularly WooHoo. They are perhaps unique in that their fears are actually wants to most other Sims (marriage, babies etc.)

The Sims 2: Nightlife

 * Pleasure: Pleasure Sims' wants are difficult to predict but almost always involve having fun.
 * Grilled Cheese: Only available via a malfunctioning ReNuYu-Senso-Orb reward object, Sims with the Grilled Cheese aspiration will want to eat grilled cheese sandwiches, or talk about them.

FreeTime

 * Grilled Cheese can be freely chosen as a secondary aspiration. Aspiration benefit points can be used to gain the ability to paint grilled cheese. Sims with grilled cheese as a primary aspiration may use benefit points to conjure grilled cheese sandwiches out of thin air.

Defunct
By using cheat codes and spawn objects, you can change your sims aspiration to "Power", which usually involves making friends and gaining promotions. However, this aspiration is not possible to get in any other way, and as such, is defunct. (Furthermore, you cannot access the aspiration bar without a reset process).