How can you participate in the transition to a sustainable society? The answer will vary for each person, and I cannot and would not suggest your course of action. However, I can tell you that the answers are both within you and all around you, and I can offer a strategy for finding them.
Either by yourself or, better, with family, friends or any group you choose, conduct one or more brainstorming sessions to explore what you can do for the environment - at home, at work and in your community and the public realm.
Brainstorming works best when there are no restrictions placed on the original creative session. "Environment" can be interpreted as widely or narrowly as you'd like, and outcomes can range from conventional environmental activities such as planting trees or making your home more energy efficient to reading nature stories to children.