I've never realized how much our thoughts control our emotions. Let me give you an example I heard the other day:
You're standing at a bus top, and there are so many people waiting with you. It's cold, crowded, and everyone's silent. You feel a sharp poke on the back of your ankle. You're annoyed but move forward a step so it doesn't happen again. A few moments later, you feel another sharp poke. You clear your throat this time, move a step away, and start to get a little angry. When it happens a third and then a fourth time, you lose it and decide to have a word with that jokester behind you.
So you turn around to look in the eyes of that person, and to your surprise, you see that it's an elderly woman, with a walking cane, and she's blind. She's using your foot as a way to keep her balance.
Immediately, your anger disappears. Even though she's continuing to poke your ankle because you've just moved again.
The point here is that the person wasn't making you angry. The fact that she was poking you in the foot wasn't making you angry either. Your thoughts made you angry.
When you turned around to see her, you stopped feeling angry. It's because you had new information, and your thoughts changed.
This blew my mind when I heard it. My whole life I've heard people say, "You control how you feel, no one can make you feel inferior without your consent" yada yada. But this, man...this finally made sense to me. Not to say I'll never feel frustrated, discouraged, lonely, or mad again. But now I understand how it works.