Just keep this, your attitude of sincere service and without a doubt Krishna will give you all intelligence to serve Him nicely. Krishna is not ungrateful but rather He sees all our efforts and appreciates our sincere service. Krishna is interested in how we engage our energies in His service. We are very small, very insignificant, so what can we do? Simply He wants to see that we are engaging our time and energy in His service.
Srila Prabhupada Letter to: Devananda - Los Angeles 23 November, 1968