This is an idiom and can't be translated directly. Spanish uses "que" and not "como". Think about it this way: does "how" make literal sense in English? It is just an exclamation you learned as a child, but is literally meaningless. If it did mean something, one would reply to the "how"... but you can't. In that respect, so is "que". Just something to memorize ;) English has other idioms like this, such as "how are you?" Again, the how is meaningless because you do not answer the "how" you answer "what you feel."