So, a sustainable lifestyle is one that can be maintained with just the resources in a small area by an individual, a family, or a small community.
This is somehow related to managing what you have to get what would help sustain you instead of getting it outside your environment. Sustainability and holistic living are very much important for our wellbeing and until we are able to get things down by ourselves so as to sustain us, we won't get to anywhere living healthily.