Since I'm in the design industry, I come across the word "sustainability" all the time - usually regarding specific building products, systems, furnishings and finishes. Sustainability has a much broader meaning than that though, and may mean something completely different to everyone who doesn't work in design or construction.
I think a broader understanding of the word acknowledges our roles as stewards of the planet and our environment and means seeking out knowledge to enable us to make informed choices - for big picture decisions (like choosing where to live) and in our daily lives (like where to shop and what food to eat).
Then, there's an even broader meaning of the word: "the capacity to endure". I love this definition (from Wikipedia) because it encompasses all of the narrower meanings relating to the environment, business practices and personal finances but also can be applied to society as a whole. Can everyone on the planet continue their own way of living indefinitely? Also, can we, as a society, continue our current processes and systems indefinitely? It's not just what we individually choose, but how we relate to each other as well.
There are some easy decisions to make, and some hard, and there's the balance of not giving up on either one if you find any of the decisions too difficult to make. If you live in the exurbs, where you have to drive for a significant amount of time just to get basic groceries, then you should still feel empowered to make lots of other decisions which will increase sustainability - like growing some herbs and vegetables, driving a fuel-efficient car, reducing consumption of plastic, etc. We can't give up on making the best choices, even if we can't make the best choice for the environment every time.
Most importantly, I see the goal of achieving sustainability in my own life as an opportunity to bring in positive change and happiness. I recently had the opportunity to meet and have dinner with Debbie Phillips, founder of Women On Fire. Her recent blog-post about adding happiness to your day rang so true for me. If I can achieve greater sustainability AND happiness at the same time, that's just incredible!
There are lots of examples to choose from, but here are some snippets of sustainability at work in my own life. Hopefully at least one of these will give you some good ideas. Trust me - if I can do any of these, so can you!