“Hold yourself responsible for a higher standard than anybody else expects of you. Never excuse yourself”.

I think what this is saying that you have to set a higher expectation than what is required by you. Also that you should not blame the things you do on others and take the blame for your own actions. To make sure you do better than what they expect from you. You have to be responsible with what is expected. I also think that this means that when you are expected to do something that you should set the standard higher and do much more. An example is that when you are caught smoking do not blame it on your friends and say they made . you should be able to take the blame for your own actions.