“You are the weakest part of your system”. That is a defeatist statement and completely untrue. It makes your expectation to fail easier to accomplish and more importantly it makes failure easier to handle. It shifts the pressure away from you and unto fate.
Would you fly on an airline if their motto was “Our pilots are the weakest part.” I do not think so. You are your system. Even if your system is automated you added the inputs, parameters.
Taking responsibility for your action is not easy. Taking control of the outcomes of trading or life is a huge responsibility. You will have moments of weakness, but you are not weak. The market does not go straight up and either does the road to success.