Just be a good person, and do the right thing. If an opportunity to do something useful and helpful to the cause of justice and equity presents itself, answer the call.
There is little else that anyone can do, unless you have political power or the ability to mobilize resources. Write to your representatives. Learn. Read.
And please, stop fretting and don’t get down. That helps no one and accomplishes nothing. When opportunities arise, you must be healthy, aware, and confident to act. Getting down and doubting yourself is counterproductive. People are angry and frustrated. Honor those feelings.
Let yourself feel those feelings. They are more valid and true than what you now seem to be feeling. Try remembering how you felt as a child. That was likely the most appropriate thing to feel.