The fourth and final rung. Even if dedicating your work to Krishna feels beyond reach, Krishna still does not abandon you. He says: take shelter in My yoga, keep your mind disciplined, and simply give up your attachment to the results of whatever you do.
Phala-tyaga — letting go of the fruit. A farmer plants seeds. Whether the monsoon arrives on time, whether the harvest is abundant or sparse — that is not in the farmer's hands. But he plants anyway. He works the soil. He does what he can, and leaves the outcome to forces beyond his control. That is phala-tyaga: full effort in the action, zero anxiety about the result.