Compassion, as far as I perceive, has more to do with the heart than the mind. It is a kind of strong emotion which well up from the innermost in the face of pain and suffering experienced by others.

It is an unconditional understanding where you feel what others feel without doubtness and usually coupled with a strong will to help.b

It is also a human nature which cannot be feigned. Only God and yourself know whether you bear a truely compassion for someone.