Doing bad things knowing that they are bad means that you are weak before your desires. When your intellect becomes mature and balanced, then you will control your desires. There is a hadees saying that Allah (s.w.t.) has created the angels and put in them reason without desire; while He create the animals and put in them desire without reason. However, He (s.w.t.) created human beings and put in them both reason and desire. So, if the human being keeps his reason controlling his desires, he will then be superior to the angels, and if he keeps his desires controlling his reason, then he will be worse than animals. If we remember the result of bad deeds, we will never commit any sin purposely.   _{Your Comment}