What does it practically mean to fix one’s mind on Krishna?

The following is an excerpt from a samvaad (dialogue) session with Acharya Prashant.

मय्यावेश्य मनो ये मां नित्ययुक्ता उपासते ।

श्रद्धया परयोपेतास्ते मे युक्ततमा मता: ।। 12.2 ।।

mayy āveśhya mano ye māṁ nitya-yuktā upāsate