Your thoughts are what you are in the invisible, the Bible says: "As a man thinks so is he’’. People will know you by your actions, but you know yourself by your intentions. That is why there are so many misunderstandings.
Your thoughts are the plan of your future, what you think will be eventually manifested in your life. That's why you have to watch over your thoughts; it’s your future direction.
You're not happy or are unfortunate because of things around you, but because of what is in you. The subject of your meditation affects your whole life and feelings.
That’s why the Bible reveals how you should think.
Philippians 4 : 8 : For the rest, brethren, whatsoever things are true, whatsoever things are noble, whatsoever things are just, whatsoever things are pure, whatsoever things are amiable, whatsoever things are of good report; if there be any virtue and if any praise, think on these things.