Newton's first law asserts that if a body is at rest or travelling at a constant speed in a straight line, it will remain at rest or continue to move in a straight path at a constant speed until acted on by a net force.
Thus, we can say that an object will not change its motion till a net force does not act on it.
The motion of a kite when the wind changes, and the motion of a ball falling down through the atmosphere are some examples of Newton's first law of motion.