It has been remarked by at least one of my colleagues that one reason we have such a hard time teaching Newtonian physics to college students is that we have to first unteach them their already prevailing world``natural'' view of physics, which dates all the way back to Aristotle.
In a nutshell and in very general terms (skipping all the ``nature is a source or cause of being moved and of being at rest'' as primary attributes, see Aristotle's Physica, book II) Aristotle considered motion or the lack thereof of an object to be innate properties of materials, according to their proportion of the big four basic elements: Earth, Air, Fire and Water. He extended the idea of the moving and the immovable to cosmology and to his Metaphysics as well.
In this primitive view of things, the observation that (most) physical objects (being ``Earth'') set in motion slow down is translated into the notion that their natural state is to be at rest, and that one has to add something from one of the other essences to produce a state of uniform motion. This was not an unreasonable hypothesis; a great deal of a person's everyday experience (then and now) is consistent with this. When we pick something up and throw it, it moves for a time and bounces, rolls, slides to a halt. We need to press down on the accelerator of a car to keep it going, adding something from the ``fire'' burning in the motor to the ``earth'' of the body of the car. Even our selves seem to run on ``something'' that goes away when we die.
Unfortunately, it is completely and totally wrong. Indeed, it is almost precisely Newton's first law stated backwards. It is very likely that the reason Newton wrote down his first law (which is otherwise a trivial consequence of his second law) is to directly confront the fallacy of Aristotle, to force the philosophers of his day to confront the fact that his theory of physics was irreconcilable with that of Aristotle, and that (since his actually worked to make precise predictions of nearly any kind of classical motion) Aristotle's physics was wrong.
This was a core component of the Enlightment, a period of a few hundred years in which Europe went from a state of almost slavish, church-endorsed belief in the infallibility and correctness of the Aristotelian world view to a state where they, for the first time, let nature speak for itself with a consistent framework with which to listen1.1. Aristotle lost, but his ideas are slow to die because they closely parallel everyday experience. The first chore for any serious student of physics is thus to unlearn this Aristotelian view of things1.2.
This is not, unfortunately, an abstract problem. It is very concrete and very current. Because I have an online physics textbook, and because physics is in some very fundamental sense the ``magic'' that makes the world work, I not infrequently am contacted by individuals how do not understand the material covered in this textbook, who do not want to do the very hard work required to master it, but who still want to be ``magicians''. So they invent their own version of the magic, usually altering the mathematically precise meanings of things like ``force'', ``work'', ``energy'' to be something else altogether that they think that they understand but that, when examined closely, no longer mean anything at all.
Usually their ``new'' physics is in fact a reversion to the physics of Aristotle. They recreate the magic of earth and air, fire and water, a magic where things slow down unless fire (energy) is added to sustain their motion or where it can be extracted from invisible an inexhaustible resources, a world where the mathematical relations between work and energy and force and acceleration do not hold. A world, in short, that violates a huge, vast, truly stupdendous body of accumulated experimental evidence including the very evidence that you yourselves will very likely observe in person in the physics labs associated with this course. A world in which things like perpetual motion machines are possible, where free lunches abound, and where humble dilettantes can be crowned ``the next Einstein'' without having a solid understanding of algebra, geometry, advanced calculus, or the physics that everybody else seems to understand perfectly.
This world does not exist. One of the most important reasons you are taking this course, whatever your long term dreams and aspirations are professionally, is to come to fully and deeply understand this. You will come to understand the magic of science, at the same time you learn to reject the notion that science is magic or vice versa. I personally find it very comforting that the individuals that take care of my body (Doctors) and who design things like jet airplanes and automobiles share a common and consistent Newtonian view of just how things work, and would find it very disturbing if any of them believed in magic, in fairies, in earth, air, fire and water as constituent elements, in ``crystal energies'', in the power of a drawn pentagram or ritually chanted words.
Let me be therefore be precise. In the physics we will study below, the natural state of ``things'' (e.g. objects made of matter) will be to move uniformly. We will learn non-Aristotelian physics, Newtonian physics. It is only when things are acted on from outside by unbalanced forces that the motion becomes non-uniform; they will speed up or slow down. By the time we are done, you will understand how this can still lead to the damping of motion observed in everyday life, why things do generally slow down. In the meantime, be aware of the problem and resist applying the Aristotelian view to real physics problems, reject ``magic'' as an acceptable component of a worldview.