Vitarka badhane pratipaksha bhavanam.
“When disturbed by negative thoughts, opposite [positive] ones should be thought of. This is pratipaksha bhavana.
— Yoga Sutra 2.33

A little practice for when life gets you down:

Sit with your spine extended, shoulders back, and heart open. Set the back of your hands to your knees or thighs, and allow the thumbs and index fingers to touch. Let whatever negative emotion or experience you want to process fully arise in you. Feel the situation or memory in every cell of your being. Really live with it. 

Release the visualization and let your breath become deep and full, slow and smooth, and then silently count each inhalation and exhalation, equalizing the two. 

Begin to notice the grace of each inhalation, of life-force entering your being. Let each breath fill you with light, love and gratitude. See your body as a sacred receptacle of your breath. Bring your awareness to your heart by crossing your palms over your chest in an embrace of your devotional center. Feel love, peace and contentment glowing from the heart and permeating your entire being.