Sustainable - an ability to be maintained at a certain rate. What do we most need to maintain? Ourselves, other living things, and planet earth, our home. Of course, there is no law that states our common home must be sustained forever; but it is both sensible and beautiful or humans and nature to live in harmony.
Conscious – about what? Consciousness is similar to awareness. Where awareness is a perception of external environment and internal processes, consciousness is deeper and involves the metaphysical. It comes from awareness and it is a more spiritual concept; from consciousness comes peace and wellbeing. It can be attained on an individual level and on societal level. As humans are uniquely capable of attaining consciousness, we have the responsability of stewardship, especially in terms of sustainability.
Development – improvement over time. Regardless of whatever we believe that events occur by coincidence or by some higher power, that things will change are certain. To refer to change as "development" would, however, require some kind of improvement over time. Ideally, that improvement should incorporate two key criteria: sustainability and consciousness.