It is impossible for us to be good unless we humbly follow a Mashpia (Chassidic mentor who is knowledgeable in the Torah and Rebbes directives, as it states, acquire for yourself a Rav/mentor!) but can’t I know what is good?! – yes and no! – you could possibly mentor someone else, but never yourself! – for whatever gives us pleasure (think of the attitude of men towards women before and after hormones kick in) literally alters our minds, and instead of seeing truth we justify, (subconsciously, so what enters into the conscious mind, is only the “truth” of the justification!)