Sometimes we can just brush that off and recover our usual good humor. And sometimes we linger in the shadows far longer than is in our best interest. One way to encourage the restoration of balance in emotion and outlook is to pay attention to the small pleasures that the day offers. Your morning "cuppa", be it tea or coffee or whatever, offers opportunity to smell and taste and savor, to be fully present in the moment. The beauty of the sky, the structure of the clouds, the way sunlight falls upon an object can feed beauty to your eyes and mind if you allow yourself to see. A favourite song, the words of a friend, the sound of birds singing can be opportunities to turn your mind to gratitude and appreciation.
If you struggle with troubling thoughts there is a Hawaiian tool for clearing past actions and memories, for assisting atonement and reconciliation. Called Ho'oponopono, the simplest approach is to run the following phrases through your mind and/or give them voice: "I am sorry. Please forgive me. I love you. And I thank you." Use these phrases to replace whatever mind chatter has been creating your distress. (For more on the Huna practice of Ho'oponopono, consult your favourite search engine.)
When we allow the externals of life to be in charge of our experience, we engage our victim archetype. Instead we could call out our natural child to see the world with wonder, or the storyteller to create a new framework for perspective, or the alchemist to transform the mundane and envision the spiritual workings of the world. We get to choose whether our locus of control is internal or external. All day long, we have the choice of where we put our attention.