“All you need in this life is ignorance and confidence; then success is sure.” Mark Twain
What this quotes means is that one will be successful if one is confident in their abilities, and ignorant of how difficult it is.
If you know something will be extremely difficult, chances are no matter how confident you are, there is doubt within you, and you may falter in your quest.
If you don’t know how difficult the journey will be, but lack confidence in yourself, chances are you will falter in your quest.
Be confident in your abilities, and remain ignorant of the difficulties in reaching your goal. You will reach your goal before you know it.