The world is habitual, systematic, things generally progress from one condition to another, if allowed to take their natural course. Without sentience, self-awareness, the chains of action and response proceed unbroken. Nuclear and chemical reactions proceed along relatively set paths with only statistical deviations from the norm; Prey graze, and in turn are fed upon by predators; Climates change, deserts expand, and deltas flood; The whole world moves inexorably along towards conclusions with only minor variance. There is a single force that changes this though; life, in particular, intelligent life. While sentient creatures are still bound by the laws of nature, they can more fully utilize the unharnessed potential of the systems they see around them. They make the possible, though improbable, less so by force of will alone.
Sentient beings, can choose; or at least possess the illusion of choice; depending on who's perspective you take, or who's version of reality you subscribe too. We are still bound to, and by, the physical world; but, we can deviate from the scripted survivalistic patterns of behavior as dictated by instinct; But only if we choose too. By understanding the fact that we exist, by the virtue that we can define ourselves and our thoughts, emotions, and behavior; we give ourselves control over not only ourselves, but over our environment; and on a scale unprecedented in "nature." This isn't to say we aren't governed by nature, or are not a part of it; everything is "natural" in some sense, since the laws of nature allow anything one might observe to exist.
But by recognizing the system, our part in it, and the rules by which it runs; we can direct, guide, improve, radically change, or even destroy. Such is the power of thought, it doesn't allow you to break the rules; but, it does allow you to realize that they're there in the first place. And even though it doesn't change the amount, or nature, of possible outcomes to any interaction; it does allow you to increase the amount of probable outcomes, and skew and manipulate the results to your desire. Self awareness is the power to discern yourself as part of, yet in some sense separate and independent of your surroundings. From a perspective of objective awareness; self awareness is the ability to determine the function of the parts of a system, and the effects its failure or optimization has on the system as a whole.
Nothing changes until we do; because, the potential to assume more and more complex states inherent in life, due to its origin in self-organizing chemical properties, is the harbinger and engine of change. And when coupled with awareness and self awareness, it is the architect of change as well. Unfortunately this potential is more often than not wasted, and events are allowed to take their "natural" course. However, nature isn't benign, its blind; species come and go, death and pain are intimate and necessary parts of it. The natural course of our evolution might be a dead end, a long drawn out death to attrition, or even self destruction...
The point is, we have the choice, and we can change things; but only if we ourselves change to better utilize our potential for the manipulation of "systems", including ourselves.