Managers cannot afford to become so enamored of position and title that they do not pick up the ball on any task that needs to be done whether or not it is in the job description.

No job is too small for a manager and leader to accomplish.  The client is paying for your time and expertise.  The consultant cannot afford to say "Not my job, man."

The customer makes the call of whether it is worth their money to pay the consultant to sweep the floor.  The consultant does not make that call.

Verse 39* of the Tao gives the project manager a meditation that can be used to center oneself in with humility.

"The pieces of a chariot are useless
     unless they work in accordance with the whole
A person's life brings nothing
     unless he lives in accordance with the whole universe
Playing one's part
     in accordance with the universe
     is true humility

So whether you are a gem in the royal court
     or a stone on the common path
If you accept your part with humility
     the glory of the universe will be yours"

Tao Te Ching, The Definitive Edition, Lao Tzu, Transaltion and commentary by Jonathan Star, Jeremy P. Tarcher/Penguin, 2001, p 32.