Anyone who says you can is engaging in hyperbole. All motion is relative to a frame of reference. It is not possible to distinguish motion with a constant velocity from rest. In general, inertia is resistance to change. In mechanics, inertia is the resistance to change in velocity or, if you prefer, the resitance to acceleration.
Objects resist changes in their motion.
Objects do not need to be pushed to keep going. In general, a force is an interaction that causes a change. In mechanics, a force is an interaction that causes a change in velocity or, if you prefer, an interaction that causes acceleration. The motion of an object won't change until a force is exerted from outside the object to cause a change. When more than one force is present it is the net, external force that matters.