Does it really matter what the motive is as long as the job gets done? Take a simple example - saying thank you to someone. In one case, it is a matter of custom and not heart-felt, in another it is to please the person, and in another case it is a genuine expression of gratitude, a recognition of the love expressed. We all know the difference. The first is sort of a dead ceremony - blah, blah; the second feels a little uncomfortable; the last motive touches the heart - feels good all around.
We consider the last motive in line with Principle, Love. It is healthful, rewarding, not just to the one expressing the gratitude, but to one receiving it.
Now consider the motive behind preparing a meal for someone else. Surely if you follow the recipe... Who can tell the difference between a meal prepared with hidden resentment, and one prepared to please someone, or one prepared for the joy of it? Everyone can tell the difference unless they have become hardened by their own personal sense - covering over what they really sense so as to keep the peace. But those who love and do not operate from the standpoint of "peace, peace where there is no peace" will not simply "swallow" the first two cases - perhaps reach out in love to the hidden resentment; perhaps rebuke the one who is constantly looking for a pat on the back ("Do you like it? I hope you like it!"). The one who prepares the meal for the joy of it, you might say, is doing it to the glory of God - in line with Principle, Love.
We can see that motive is hugely important - difference between a good and bad motive like the difference between night and day. The degree to which one is aware of this indicates the degree of spirituality, the extent to which that one is operating from the standpoint of spiritual sense, instead of blind personal sense!