Sustainability has two meanings. On the one hand, it refers to ability to sustain, to keep up with certain action or process. In this case it would be keep going to aim towards more earth-friendly lifestyle. It is about lasting change.

On the other hand, it could be approached as the overall outcome of the transition to more earth-friendly living. As stated in the dictionary, sustainability refers to “the quality of not being harmful to the environment or depleting natural resources, and thereby supporting long-term ecological balance”