Imagine you are sitting on a recliner chair watching your favorite movie or show and your mom calls out your name and asks you to run some errands. You can imagine how difficult it would be for you to get up and do the work. Imagine you are practicing for a 100-meter race on the track and somebody asks you to stop immediately within a second. will you be able to do it? what if you are suddenly asked to turn right? will you be able to turn immediately? The answer to both questions would be NO. You can stop yes, but gradually. You can also turn but not sharply. And guess what it's the same story with every object. Every object will continue to do what it's doing.
If it's at rest it will remain at rest and if it's in motion it will remain in motion. But what can change this? only an unbalanced force can change this. If it's at rest and an unbalanced force is applied it will move. If it's in a constant motion and an unbalanced force acts on it, it may accelerate or change direction. And this is nothing but Newton's first law of motion. The correct definition is " An object is at rest it stays at rest and an object is in motion it will remain in motion with the same speed and direction unless acted upon by an unbalanced force. In simple words, it means an object continues to do what it was doing unless some external unbalanced force is applied to it. It is also known as the inertia of motion.
some examples of the first law of motion :
Breaks applied by the bus driver.
object placed on a plane surface.
Marathoner running beyond the finish line.
A ball rolling on the ground.
An object is thrown into outer space.
Washing machine dryer