This is an admonition that seems almost contrary to what you expect. The point is that your goals must be established before the Work begins, and during the ritual focus only on it, not the goal.

The "lust for result" refers to the fact that pure will is expressed in a love of doing rather than looking for rewards or consequences. Both Wagner and Shakespeare expressed their true genius purely for the love of expressing it, and with no pressing motive of gain or "lust of result." Those possessed by the lust of result are rendered desperate and impatient; and they wind up in disillusionment.