The compassion we feel normally is biased and mixed with attachment. Genuine compassion flows towards all living beings, particularly your enemies. If I try to develop compassion towards my enemy, it may not benefit him directly, he may not even be aware of it. But it will immediately benefit me by calming my mind. On the other hand, if I dwell on how awful everything is, I immediately lose my peace of mind.
The chief helps in this liberation are Abhyasa and Vairagya. Vairagya is non - attachment to life, because it is the will to enjoy that brings all this bondage in its train; and Abhyasa is constant practice of any one of the Yogas.