If you want to ruin your life from the inside out, start here: Be Nihilistic - Believe That Nothing Really Matters. Tell yourself that life has no meaning, no purpose and that your choices are insignificant. Mock hope. Decide that right and wrong are just opinions, that morality is subjective and that nothing you do, good or bad, really matters in the end. So why try? Why care?

Treat all beliefs as equally meaningless or irrelevant and stop seeking truth. Silence your conscience urging you toward goodness and love. Ignore it. Numb it. Laugh it off. Float through life without anchoring to anything solid; believing that life is meaningless and that there's no real purpose, value,or truth to anything.