We present a way to reach the maximum possible critical current density, Jc , for YBa2Cu3O6+x (YBCO) thin films. This value is found to be around ten times the currently reached values. It is found that the Jc}(0 T) is governed by the mean free path of the electrons, as is the critical temperature, Tc . The Jc in field, on the other hand, is governed by flux pinning and can be enhanced by optimizing the size and distribution of the non-superconducting nanoinclusions. By optimizing both the mean free path and the pinning structure, the maximum values can be reached