The faith which is needed…

It is this faith that you need to develop—a faith which is in accordance with reason and common sense—that if the Divine exists and has called you to the Path, (as is evident), then there must be a Divine Guidance behind and through and in spite of all difficulties you will arrive. Not to listen to the hostile voices that suggest failure or to the voices of impatient, vital haste that echo them, not to believe that because great difficulties are there, there can be no success or that because the Divine has not yet shown himself he will never show himself, but to take the position that everyone takes when he fixes his mind on a great and difficult goal, “I will go on till I succeed—all difficulties not withstanding.” To which the believer in the Divine adds, “The Divine exists, my following after the Divine cannot fail. I will go on through everything till I find him.”

Ref : Letters on Yoga Vol. II