Consider for a moment that you have poured a little water into a vessel; when the vessel moves, the water also moves. If the vessel is steady then the water remains steady. In steady water you will be able to get your own image. In moving water your image will be moving and therefore it will be indistinct. It follows then, that if you want to enter into the still state of meditation and have a vision of your true Self, you must keep your body steady. The body is like a vessel; the mind may be compared to the water inside. If the body moves it is like the movement of the vessel; the mind inside will then also move. Therefore if you want to keep your mind steady, you must keep your body steady. Considering how much you move the body, think of how much more the mind will move.
If you throw a stone into a well, ripples will start. These ripples or waves, which come on account of the stone hitting the water, will soon spread to the far end of the well. In the same way, once you put a thought into the well of your mind, it spreads to the entire body. And whatever be your thoughts, they will subsequently influence your actions. So, you must constantly keep good thoughts in your mind. When you are having good thoughts, then there will also be good feelings in your heart. If bad thoughts enter your mind, then in whatever you see, in whatever you hear, in whatever you talk and wherever you go, these bad thoughts will lead to bad actions and grievous results. (DBG, p. 216)
Be steady in sadhana and never hesitate once you have decided on it. When the bus is moving on, the dust will be floating behind as a cloud. It is only when it stops with a jerk that the dust will envelope the faces of the passengers. So keep moving, keep steadily engaged in sadhana, then the cloudy dust of the objective world will not cover your face. (FDD, pp. B-9)