Newton’s laws of motion:

          A body continues its state of rest or uniform motion in a straight line provided no net force acts on it.

Examples:

Case I (Part I):

According to Newton's first law of motion, a body at rest remains at rest provided no net force acts on it. This part of the law is true as we observe that objects do not move by themselves unless someone moves them. For example, a book lying on a table remains at rest as long as no net force acts on it.

Case II (Part II):

 Similarly, a moving object does not stop moving by itself. A ball rolled on the rough ground stops earlier than that rolled on smooth ground. It is because rough surfaces offer greater friction. If there would be no force to oppose the motion of a body then the moving body would never stop.