Compassion is one of the hardest things to accomplish, not only towards others but also towards oneself. Fear and other conflictive emotions and beliefs makes us feel separate from one another (and from ourselves!) when the truth is that we are all connected within us and with all others. Those emotions and beliefs damage our image of ourselves creating a lot of unnecessary pain and suffering.
The practice of compassion, even amidst the most difficult and painful moments, can for sure ease that suffering and open new perceptions of people and situations. So practice compassion, be compassionate whenever it is possible to be and if not possible, be compassionate about your own inability to be compassionate.
We are all human, none of us is perfect and flawless and there are moments in which we simply cannot be compassionate. Maybe there's a need, for some reason, to not be compassionate at that time. However this does not meen we shouldn't strive to be the best of ourselves at all times.
To be the best version of oneself at all times is a treasure we offer not only to the world but to ourselves and our lives.