Strive for nirbandhini mati even during vaidhi bhakti

The mentality during vaidhi bhakti  of exclusive  cultivation of devotion with  the aim of achieving bhava  bhakti, and  the  mentality  during bhava  bhakti  of  intense cultivation with  the  aim  of achieving prema, is called  nirbandhini mati  or undivided attention.  If such  concentration exists,  then  very  quickly    the  devotee attains   perfection.  In other words the devotee must  make   an effort  corresponding to the goal he wishes  to achieve. From  the  very  beginning of  practice, the  devotee must   adopt this  concentrated attention, and should beware of  giving  it up due to inattention.

Chaitanya Shikshamrita, Bhaktivinoda Thakura