Recognize accomplishments in the Sunday service. Make use of a variety of approaches to doing social justice work including service, education, advocacy, and developing community organizing. Set up an effective structure for your committee and task group by selecting effective leaders and preparing job descriptions for both your committee and task group. Make sure the meetings are well run with a structured agenda and a careful use of time. Set up a workable structure but don't get bogged down in your structure.
Most people are more interested in doing things than sitting in meetings.
Let people use their energy in task groups on specific issues instead of trying to get everything done in one social justice committee. Make fun a part of your meetings. Have a social time before your meetings and serve food. Celebrate what your groups achieve with parties and other fun events. Build spiritual nurture into the structure of your meetings.