After activating the “testingCheatsenabled true” code, you can shift + click on the mailbox, your self, your workplace, or even the ground.
Shift clicking the mailbox with the testing cheats enabled gives you a whack of options. You can change your career, level included. You can max out everyone in the households’ needs with Make All Happy, and keep them there, or allow them to change, with Make Moods Static/Dynamic.
If you’re lonely, you can force a visit from a Sim or NPC (pizza deliver guy, paperboy, even the Grim Reaper). You can also become acquainted with everyone in town or get a few random friends.