Karuna is when you see suffering in yourself and when you see suffering in others, doing something to overcome your own suffering and doing something to overcome the suffering of others. This is developing the quality of Karuna, compassion.
In this modern world, where there is a lot of suffering, and the suffering manifests itself in many different ways, it is extremely important to develop this quality of Karuna in relation to others and in relation to your own suffering. In this connection the Buddha has said: Helping others is helping yourself; helping yourself is helping others. And eventually you see no difference between yourself and others.