volenti non fit iniuria

Latin: "to a willing person, injury is not done"

This is a law term, but it is relevant in most endeavours. Injury in the context here doesn't necessarily mean physical injury, but the fact that you are going to lose, you are going to punched in the face, you are going to get criticism, you are going to get slammed and you are going to hurt. 

To a willing person, injury is not done. 

Accept that these things are going to happen, prior to them happening, and then they have no power over you if, and when, they happen. 

Be willing to take the knocks, and injury is not done. 

Andrew Whiteman