I happened to have a friend who is permanently calm.
His car brakes down unexpectedly? No problem. Running late with deadlines at work? No problem. The world crumbles and falls apart? No problem: grab a bucket of popcorn, sit calmly and observe. For years, I thought that my friend was a brute who didn't care much about anything. It was far from the truth.
How many times have you found yourself in a bad mood for "no good reason"? We need to learn to discipline our thoughts and keep them in check. This way we can make a mindful decision to be happy and feel good. By changing even the smallest thing now, we can improve all our tomorrows.