There’s no such thing as an obligation you didn’t choose. You could say that you didn’t choose to be born–and that it’s therefore your obligation to thrive and survive. But even this is a choice. You can commit suicide; even though most won’t make this choice, it still is an option. You can simply decide to let others provide for your welfare; that’s a choice, too. The choice to thrive and survive isn’t an obligation so much as an “if-then” proposition. IF you want to survive, THEN you have to provide for your welfare. IF you want to thrive and be happy, THEN you have to live your life by a consistently applied set of rational principles, in the context of a free society.
It’s true that others will assert that you have obligations whether you choose them or not. Some will say you have obligations to a supernatural power–and therefore you must follow the dictates of an entirely secular power who claims to represent that supernatural force. Others will say you have an unchosen obligation to “society” or to everyone in general. But it’s really your choice as to whether to accept or believe this. Again, if-then propositions are involved. IF you want to be free and happy, THEN you have to reject the idea that you owe your life to others who seek to make such a claim on your life.
In moral and psychological terms, obligations are chosen.