Why do we think we aren't able to do something when we don't know yet if we are capable?

I receive a lot of advice in my life and there is one person who gives me the advice to do something that I thought I wouldn’t be able to do. It was my guidance counselor in secondary five when I came to her office for my college choice. When I told her that I was hesitating between two cegeps to continue my studies, she looked at my grades, to see how school was going for me. She then said, "Why don't you try Champlain, a cegep in English? you have one of the best Grades in English of all Secondary 5." I told her that I didn't want to put too much pressure on myself for my first year of…