Just as we do not refuse to serve because of our liabilities, so we do not agree to serve because of our assets. We agree to serve because of His assets. That is the natural way. Most of us would say it is flawed because of the word guess . Training and ability contribute greatly to service, but they do not prepare you for it.
Preparation happens in the mind and heart.
Yielding has nothing to do with feeling or desire. It has everything to do with obedience. Yielding is an act of the will. You begin with an initial commitment to serve God whenever, wherever, however, for ever. As specific calls reach your heart, they find a pre-conditioned audience.