It’s an old way of saying that nobody knows you better than you and if you have already made up your mind to do something and your killer instincts are giving you a green signal then instead of paying a ear to someone ask your inner voice first.
Half of things get done if you have a will to get them done. You are already half there if you think you can and eventually you will if you don’t stop until you reach there. Instincts always have an edge over somebody’s advice because you know evidently that what are your strengths and what are your weaknesses.
And when you want to embark on a venture that gives you a lot of second thoughts, rather than asking someone ask yourself what will be your weaknesses if you embark on it and would you overcome if they came across you? Wouldn’t you give up no matter what happens?
It’s all in the mind and nothing is mind over matter. One's mind is itself is capable of accomplishing infinite limitations brought on by the environment. The limitations whether they are physical or mental hinder us from reaching our full potential. Therefore, it is important for us to believe that we are nothing less than powerful in our determination and grit to succeed.
However, it’s not like that you should never listen to someone’s advice but paying first attention to your inner voice should be your first call.