But doesn't that mean we'll become totally ignorant of all the shit that is going on in the world and wont be able to change any of it because our heads will be in some cloud? No.

Positive means concentrating on what you can do to make things better. Negative is when you are always looking at the shit side of things and wallowing in self-pity waiting for the world to do you a favour.

Positive thinking does not deny that shit things happen in the world, it's a constructive way of developing the world.

Positive thinking should apply to all aspects of your life. Especially to your interpersonal relationships. Don't let bad experiences with people get you down. Don't get hurt by being rejected. You are never rejected in totality, there is always another opportunity.

Don't get all morose and sad about the fact that no-one likes you. This is a lazy attitude to life. Here you are expecting that the world should do you a favour and make you happy. Make yourself a happy. Be content with yourself. Love yourself.

Don't think about what people can do for you. Think about what you are going to do for yourself. People will only love you if you make the effort to love and be happy with yourself, for without doing the latter you cannot ever believe that other people can love you.