What the Cause needs is such ardent and self-sacrificing servants and not lukewarm followers who are ready to reap the fruit...

"What the Cause needs is such ardent and self-sacrificing servants and not lukewarm followers who are ready to reap the fruit but unwilling to take a part in winning that victory. Shoghi Effendi, therefore, hopes that you will endeavour to make of your spiritual children of the type Bahá'u'lláh sought to have and create not passive admirers but active servants of the new world order."

(From a letter written on behalf of Shoghi Effendi to an individual believer, November 6, 1932)

http://bahai-library.com/hornby_lights_guidance&chapter=2#n384