For example, if you are concerned about racial discrimination, do some soul searching and think about how you can be fairer to people of other races in your own life. Are there racist stereotypes that are affecting your own behavior? If so, you can make a conscious effort to treat people more fairly.
Nobody is perfect, and in the complex world we live in, it's difficult to avoid all injustice. If you pay taxes, chances are, some of that money is going to go toward something you disagree with, regardless of your beliefs. Do your best not to contribute to injustices in any way you can avoid, but don't let yourself be immobilized by a need for perfection.
