如人饮水冷暖自知
[rú rén yĭn shuĭ lĕng nuăn zì zhī]
'Rú rén yǐn shuǐ lěng nuǎn zì zhī' translates to 'Only one knows if the water he drinks is cold or warm'. It expresses that only the individual can fully understand their own experiences or feelings; others cannot fully grasp what they go through internally.