Novel write verification methods are proposed to improve write speed, energy and endurance of resistive random access memory (ReRAM). Flexible write stress is implemented during reset w/ verification and set w/ verification, by which the pulse width or voltage can be decremented as well as incremented. Proposed reset w/ verification and set w/ verification methods are characterized by measuring 50nm AlxOy ReRAM devices and compared against conventional methods. Improvements of 1.9× average endurance increase, or 1.4× average endurance increase with 17% write time, the reset time plus set time decrease and 17% average write energy reduction are demonstrated.