Christians and mercy?

As Christians, do you ever find it hard to have mercy and compion for people who perpetrate so much pain and suffering? For example, as a Christian, I know that we are required to love our enemies and be forgiving but it is an ongoing struggle when I see so much evil carried out, i.e. the Tucson shootings. As a Christian, what is your perspective? Do you find these areas of compion and Christian forgiveness easy or difficult for you?