Can you fail at wanting to do something? No, it is impossible to fail at wanting to do something. When everything is said and done, what your heart of hearts wants is to have no doubts whatsoever that you spent your life wanting God's life. There is no such thing as failure in a sincere wish for God's life; in truth, the success is in the wish itself.
A sincere wish holds no fear, unless it becomes a demand. But if the wish remains pure as it is intended to, then nothing can touch it. If on the other hand you reject the opportunity to receive what you have wished for, then you will be responsible for that rejection, and yet in that same moment you will be given the opportunity to strengthen your original wish to want God's life more than you want anything else.