So sadhana, in this remembrance is the key word.
That is why sadhana is so important; continuously and correctly doing sadhana - correctly.
What is the correct way of doing sadhana?
Bring the Divine form in your mind, in your heart (and) doing roopdhyan, remembering the Divine love, the Divine pastimes, the Divine glories, the Divine beauty of the Divine beloved lord, chant His glories, listen to His Divine pastimes, etc.
Shravan and kirtan bhakti are the greatest helpers to get our sumiran bhakti strong. That’s the aim, to get sumiran strong. Remembrance through roopdhyan, and then the roopdhyan may become so very easy to us with this practice of sadhana.