Sleep
Sleep is similar to the role-player or glue-guy on a championship team - it doesn't need any praise or gets a lot of attention, but without it, there is no championship. You can have the most optimal diet, impeccable physical preparation and recovery, and a mamba mentality, but if you are not utilizing the countless recovery effects of a proper sleep, you will not be your best self. It is the glue that brings the four recovery pillars together and allows you to squeeze out every bit of potential.