It is your thoughts that make you what you are and impact immensely the person you are becoming. Your thoughts if repeated can become imprinted onto your mind, creating who and what you are, your beliefs, behaviour, and actions.
You should at all times try to control your thought patterns, for if they are left alone to run free they may create a reality that you really don't care for. Thoughts are yours to have full control over and not allow external influencers to manipulate them; others may try to hijack then impact or manipulate your reality via your thoughts.
control those thoughts and not the others around you want. With nurturing and care really profound thoughts can be yours, to enlighten your life, solve your problems, creating the ideas and plans that can truly change your life for the better; making your reality match your desires.
Your thoughts become your words and deeds, your very self, your persona that others recognize; so, for this reason, you should always take care of what you think, and what influences you to expose your minds to.