With the word I can't, one has already shut the creative ability in him to give a trier. If we are filled with positive attitude towards learning anything in life, mastering it would become so easy.
Back then in secondary school, I hate mathematics, I used to publicly saying it that I can't know it and I don't know it as a result. On getting to college, I changed my perspective towards it, I developed a desire to know it, and that desire led to improvement in my mathematics.