sadhana can simply be a daily spiritual practice. a commitment to practicing the yoga. mind you, yoga is not limited to the type of practice in which you put on certain clothes, roll out a mat, and move your body into a sequence of postures. it can be. and there are many more ways to attune yourself to what is coming to you.
the modern lifestyle (physically demanding, spiritually taxing) in which many of us engage—and become victim to—does not always serve the awakening process. it stops serving us when external forces start owning us. when we give our sovereignty over to the ego and possessions, we lose contact with the truth, the energy which binds the entire universe.
sadhana is about opening your receiving channels and listening to your higher self, in the most basic way.