One should follow in the footsteps of previous devotees regarding how to worship the Supreme Lord with the prescribed paraphernalia, or one should offer worship within the heart by reciting the mantra to the Personality of Godhead, who is nondifferent from the mantra.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
परिचर्या भगवतो यावत्यः पूर्वसेविताः । ता मन्त्रहृदयेनैव प्रयुञ्ज्यान्मन्त्रमूर्तये
paricaryā bhagavato yāvatyaḥ pūrvasevitāḥ | tā mantrahṛdayenaiva prayuñjyānmantramūrtaye
SB 4.8.58