In Sunmi's Who Am I, the first words of the song are
애써 아무렇지 않은 척 / 쿨한 척 센 척은 필요 없어
which is apparently translated as "You don't need to pretend nothing's wrong, you don't need to pretend to be cool". So I'm inferring 애써 아무렇지 않다 is a phrase to mean nothing's wrong. However, I cannot figure the meaning from 애써 (dictionaries give 애쓰다 'make an effort to achieve something') and 아무렇다 ('being in an indefinite condition or situation'). I cannot figure out the meaning of the phrase from its components, so what I ask is how should I properly understand it. Feel free to correct any mistake I made.