Guilt

Guilt should be the one prime defining force in your life (and should always be closely accompanied by shame and fear). It should be the reason you don't do anything you want, and it should be the reason you do everything you hate. Every decision you make should be decided by your own interminable guilt over existence, and all the little guilts in between.

For instance, as a kid, you should force yourself to get good grades not because you want to exceed but because of guilt over disappointing your parents with anything but perfect report cards. When you go to college, you should choose a major that sounds good (something science-y, maybe) but in which you have no actual interest. (Or ensure your future failure by picking the most masturbatory subject you can. Like English. Or Philosophy. In a way, that's almost preferable, because then you get to spend the rest of your life seeing the awfulness that happens when you make a decision not based on guilt.)

At your job, you should work overtime despite the fact that you don't get paid for overtime, and you should work harder when everyone around you sucks because you feel guilty over letting anybody down. You should donate money, extra organs, blood, and anything else you can that doesn't actually involve time not because you're a good person but because of your guilt over being a bad person. You're a bad person because your life doesn't suck quite as bad as the people who need these donations. You're a bad person because when you look at a fat person, you think to yourself, "Wow, that person is fat." You're also a bad person because you hate all the assholes around you.

As previously mentioned, guilt should also keep you from doing anything that makes you happy. Or it should at least lessen the pleasure you get from anything. This includes, among other things, smoking, drinking, drugs, eating, sex, watching TV, driving, buying things, not buying things, laughing at people, using the Internet, sleeping. You should consider all the bad consequences of all of these things as you do them, thereby nullifying whatever you enjoyed about them in the first place.

Yes, guilt should be behind every action and inaction in your life. But as bad as that sounds, remember that guilt is also probably the reason you haven't killed yourself yet.