If we take a sense of universal altruism seriously, where is there room to have enemies? Our real enemies and the enemies of humanity are negative emotions like anger and hatred. Indeed, people who are dominated by powerful negative emotions should be objects of our compassion.
We have to remember that each and every one of us is part of humanity. We must be determined to achieve positive change, but also to take a long view of what needs to be done. What is important is not to become demoralized. Optimism leads to success; pessimism leads to defeat.