I am LGBT and I have seen with my own eyes over the past decade alone the sheer amount of change that has been happening, largely to citizen activism and perhaps assisted by the popularity of the Internet and social media. It is amazing the kind of change people can bring forth as a group.
Citizen activism is a good way to promote social justice and may be the best way. As a citizen activist, you can fight for what you believe in and get others to back you so that your social causes can lead to social justice. It just may not work all the time and you have to prepare yourself for that failure. I know of several people who actively pushed companies to make things better and with help from their friends, did get a form of justice when a little girl died. So it is possible, you just have to work hard to get it.