We cannot keep taking and taking and taking resources from the natural world, simultaneously pollute it, and expect Mother Nature to be okay with it.
Less bad is not good enough:
We need to strive for a better world, not by fixing problems in the "band-aid" fashion - mitigating the issues instead of digging deep, getting our hands dirty and being uncomfortable with the mess we've made to help inspire us to drive real positive change. We need to design in a way that is better for our planet, allowing it to not only survive but thrive.
Curiosity is key:
We live in a world where sustainability has become a buzzword, and consumer products specifically are being greenwashed left and right, with good marketing consumers are left to believe a lot of "alternative facts." As both a consumer and a designer, understanding the right questions to ask in the first place is key to driving positive sustainable change, we become a danger to ourselves, the planet and each other if we take all information at face value.
There is no box:
This is a philosophy my own father lives by, and I think it works well in the world of sustainable design thinking. The most impactful and innovative changes that happen in the world of sustainability and sustainable product design so oftentimes happen in areas of the system we don't expect or think of on the surface as great areas of impact - when we think outside the box!
Working backwards and employing a lifecycle systems approach to design can help uncover less discovered areas of impact for effective sustainable design intervention.
Nature knows what's up:
By looking to nature to help solve various design problems, radically innovative and different design solutions can occur to solve a variety of (often times, man-made) problems. Design not only inspired by nature but integrated with nature will help us drive towards a more successful and sustainable future.