yes our biggest philosophical mystery has always been meaning of life. pursuit of purpose becoming your pursuit kind of becomes circular reasoning which is a logical fallacy. but it's like camus said in myth of sissyphus, sisspyphus rolls the stone with all his effort to top of the hill only to see it roll down the hill.. but he again must roll the stone back to the hill..
are you studying philosophy or just thinking
p.s. u r welcome.. mind you i'm not gud in philosophy.. just that i've read a few books here and there..