With the exception of very few who have gained higher spiritual tendencies in prior lives, Self-realization is not possible for anyone without the blessings of a guru. Think of the guru as the manifestation of God in this world. Take even the most insignificant word of the guru as an order and obey it. That is the real service to the guru. There is no greater austerity. The guru's blessings flow automatically to any obedient disciple. That is the real service to the guru.