To travel in another country, you need visa permission, similarly to go back to Godhead you need permission & mercy from his pure devotee.
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. — The Nectar of Devotion, Page 14.
Our own endeavours can only take us to a certain level but ultimate goal will be attained only by the mercy of Vaishnavas and mercy of Krishna.