No one teaches us that we are in charge of our thoughts - and can selectively choose which ones to think.
When you are driving down a road and someone comes flying up behind you and flashes you to move faster - how do you feel and react?
Your feeling is triggered by what you are thinking.
If you're annoyed, your thought might be, "I've had a LONG day - screw you. Slow down." Your heart might race. Your thoughts bounce around your head frantically.
Perhaps the driver's mother was just rushed to the hospital.
Does it change the way you think / feel? When you think that thought, perhaps you feel compassion and abiding. You heart is peaceful and your mind is clear.
Just like that you can change your emotional state. By choosing a higher quality thought, you get to feel good.
Doesn't matter why that driver was rushing. You get to choose how you think / feel / act.
It's awesome, right?