How do I find an external cause to devote my life to or is it not worth it?

Yesterday I heard a clip in which Zizek says that the purpose of life shouldn’t be getting to know oneself or else one gets stuck in a never ending cycle if narcissism. The purpose of psychotherapy should be to get to know oneself in such a way so that one can devote oneself to an external cause. Now I want to look for an external cause to devote my life to but i cannot seem to find any. The question is should I? Is it even worth it? I can’t seem to find anything worth devoting my life to even though my life doesn’t amount to much. Maybe I don’t have enough empathy for people. Maybe I am just selfish. I have tried my whole life till now to get to know myself better and to understand other humans. i always get what i want but life seems idk empty.