Humbleness is the sign of progress in Krishna Consciousness. A Krishna Consciousness person thinks always about himself as the lowest creature in the world, and the more one thinks like that he becomes elevated more and more.

A Krishna Conscious person is never falsely puffed-up; he is satisfied with his humble position as the servant of the servant of the servant of Krishna.
-  Correspondence, Allston, June 1968

 Sannyasi should go on preaching, preaching, preaching, preaching. Practically, I was sitting here in Vrindävana, in Radha-Damodara temple. So at the age of seventy years, nobody goes out. At least from Vrindävana nobody goes at the age of seventy years. But Krishna asked me. I thought that I must go, Guru Maharaja wanted it, Caitanya Mahaprabhu... Let me try. So if I had not gone then this institution would not have developed. So this is practical.
Room Conversation -- September 5, 1976, Vrindavana

"We are not always successful in our attempts in preaching work, but such failures are not certainly ludicrous. In the Absolute field both success and failures are glorious."
Prabhupada Letters : 1966.