Issac Newton said that if we take away all outside forces such as friction or air resistance, things continue to move in a constant velocity forever. He called it the first law of motion, or inertia.
In other words, an object at rest will remain at rest unless acted on by an unbalanced force. Conversely, an object in motion continues in motion (with the same speed and in the same direction) unless acted upon by an unbalanced force that act on it to stop it. Therefore, a natural state of any object is to keep doing what it is doing.
Empirically, the same principle can be applied to human beings.
Paul Graham says,
One of the tricks to surviving a grueling process is not to stop and think how tired you are. Instead you get into a sort of flow. Imagine what it would do to you if at mile 20 of a marathon, someone ran up beside you and said “You must feel really tired. Would you like to stop and take a rest?”
Well said… I think he is pretty good at coming up with the perfect analogy. Anyway, if we stop along the way, it is harder to restart and keep running. So let’s just keep running. Life is a marathon not a sprint!
Conversely, if you start a bad habit even a second, it is likely that you keep doing it. If you allow yourself to watch a comedy show or whatever even for 10 minutes, it is likely that you continue to watch it more than 10 minutes.
So the take away here is, don’t stop good habits, and don’t start bad habits even a second.