You can intuitively "connect" with inorganic and organic beings of your choice, allowing you to exchange their current acceleration and velocity at your behest. For instance, you can go abnormally fast by linking yourself to a moving car or plane at the expense of making them immobile. You could abuse this to slow people down by linking them to objects in their rest state. Your mind and body gain the necessary physiology to react and adapt to the changing speeds. However, the longer you attempt to maintain it, the more likely you will suffer from mental and physical damages.
Note: Trying to attach yourself to photons in an attempt to move at light-speed would only go horribly wrong as your body would be rendered near mass-less, leaving your mind in a vegetative state.