Bié fèijìn xīnjī le, zhè jiàn shì shì gǎibiàn bù liǎo de.
Stop racking your brain over this — it can't be changed.
Tips
usage
心机 has a mildly negative connotation when used alone (implying scheming or hidden agendas). But in phrases like 费尽心机 (to rack one's brains) or 用尽心机, it simply means great mental effort without necessarily implying deception.
