Energy:How does potential energy become kinetic?

Energy transforms from potential energy to kinetic simple by having something act upon it. If I  picked up a marker and then threw it, its energy would be kinetic. However, when I wasn't moving it, its energy was potential. Since it wasn't moving, it would only have potential energy until something acted upon it. If noting acted upon a object like the marker that couldn't make kinetic energy, that object would never have anything but potential energy. The name of the kind of energy is self explanatory, potential energy. The potential to make energy. Heres a link explaining http://sciencenetlinks.com/lessons/transforming-energy/