Have you ever lost trust in others? If you say "No", you are a really happy people. I say "Yes". I used to be very depressed when I discovered the fact that I was tricked by a friend who I loved and esteemed very much. I was wounded. Everything around me seemed to turn to grey, the joy had gone as well. I did not know what I could do but cry for anger. After that injury I learned the way to stand up by building myself trust. Building trust by thinking positively and giving trust do me a good in life.
No one does not experience sadness, it will come sooner or later. You can not avoid it but just face it. Thinking positively help me overcome sadness effectively. I tell me that there is nothing too serious, "as a door close, another one will open". Moreover, living in negative thoughts is really profitless.
It will just kill myself and my hope. When a friend hurts me, I will talk to myself that I am very lucky because I soon learn how bad she is, in order to keep away from her. She's at a disadvantage as she does not have a good friend as me.
One of my friends told me that it was very miserable when he could not trust anyone. Always making doubt led him to loneliness for a long time. That made him want to be crazy. He advised me: "giving your trust, it will turn back to you". Everything has its two sides, you want to receive, you have to give in advance. I give trust by keeping a promise if I make it and being frank with myself. Noone wants to be cheated and keeping promise show that you are trustworthy...