Think about how many times you have been upset over trivial matters and ruined your day walking around with a long face and in a lousy mood that would have affected not only you but also those close to you.
On hindsight, you may feel terrible about having done that. You may even resolve not to let such a situation trap you again. Resolves are fine, but you do need something to sustain the resolve? And what is that something?
The next time you catch yourself feeling blue consciously detach yourself from the situation and take an objective look at it. You will be able to rationalize the situation. Once you do so you are working upwards and you will find yourself climbing out from the depths of despair that the situation has plunged you into. Let your guiding thought be ‘tough times do not last only tough people do’.