1. Recognizing that all living beings have been our mother
2. Recollecting their kindness
3. Wishing to repay this kindness
4. Heart-warming love
6. Great resolve
7. Bodhichitta, the mind wishing to become enlightened in order to benefit sentient beings
These seven components of the practice seem to me a great outline for opening the heart. Even if we are not willing or able (due to philosophical issues or inborn conditioning) to commit ourselves to liberation for the benefit of others, the cultivation of bodhicitta yet points to the fact that an enlightened heart is a loving and compassionate one.