Greatest Enemy in spiritual life is egoism and lethargy.
In the preliminary phase of spiritual life there are different kinds of austerities, penances and similar processes for attaining self-realization. However, even if an executor of these processes is without any material desire, he still cannot achieve devotional service and aspiring by oneself alone to achieve devotional service is also not very hopeful, because Krishna does not agree to award devotional service to merely anyone. Krishna can easily offer a person material happiness or even liberation, but He does not agree very easily to award a person engagement in His devotional service. Devotional service can in fact be attained only through the mercy of a pure devotee.
Austerities create character in a devotee’s Life and Character attracts Heart of God. To the degree the Austerities give you discomfort and you sacrifice to that degree you will progress in your spiritual life of devotion to Sri Hari.
The beginning of Spiritual Life happens when we develop interest and taste for things, words and association that are beyond the relativity of this world. Then the “Antaryami” Lord residing in us guides us and directs us depending upon our desire to Guru, Sadhu & Shastra. Then we develop this faith with certainty that I am this spirit soul and who belongs as an eternal servant to Krishna
Spiritual life is not dry, it is also exceuted happily, 'susukham'. The result of that is not just happiness, but bliss, spiritual joy.
In the devotional service of the Lord, the only qualification required is surrender. Surrendering oneself is in one’s hand. If one likes, he can surrender immediately, without delay and that begins his spiritual life.