“Vitrka badhane pratpaksa bhavanam. When disturbed by negative thinking, think the opposite.” -Yoga Sutra II:33
This sutra is a very basic, very practical way of dealing with negative thoughts. Those creeping feelings of jealousy, hatred, anger and pessimism that inevitably rise up within our minds can be dealt with through the age-old, ancient wisdom of this sutra. Think the opposite. If you are feeling sorry for yourself transform it into feelings of gratitude for everything you have. If you are feeling jealous of someone, transform it into delight at their situation. If you are being judgmental, see if you can temper it with compassion and sympathy.
In the everyday battle to control our minds and stay on the path of yoga, there are days when it is easy to feel the bliss that is our true nature and there are days when that sense of joy is completely buried and on the verge of suffocation. We have to deal with the darkness by focusing more intently on the light, in the most practical and effective ways. Change your thinking and you change everything.