Being content does not mean being lazy.
Being content is the first step. The next step is to apply effort according to priorities. Discontent means an inability to think clearly. Hence if discontent is a motivator, contentment will take you many steps further.
Accepting whatever is, will help us relax and face life's challenges with a calm mind. Hence we will learn our lessons faster than if we spent time resisting what is.
I have practiced this for last five years and it has worked. Circumstances have changed dramatically and I have got more than I could imagine out of life.
I continue to make and effort and not rest on my oars. I am just doing it in a more relaxed way, instead of being stressed out.