We could decrease our rate of consumption/production, for one. The rate at which we're consuming is what's unsustainable. We have enough resources today to cover everyone's needs. The problem is we are producing well past that, and even still not everyone is getting what they need. Just look at how much food is thrown into dumpsters every day. Or all the energy locked up in landfills in the form of deteriorating plastics and electronics. All the junkyards filled with cars. Look at the thousands of acres of almond farms in CA's central valley. It takes a gallon of water to grow a single almond, yet the central valley is in perpetual drought. A better allocation of resources is what's needed.

We live in a society where everything is disposable, and that has a huge energy cost that we don't factor in because energy is so cheap right now. When energy is more expensive, repairing, conserving, and reusing a thing will be a better choice instead of throwing it out and buying a new one.