Practical action is the best way to show our determination. So while chanting, we should show our determination to be attentive. This attracts Krishna's attention.
By chanting of Hare Krishna, you have the Lord with you and He satisfies you. He pleases you. You are pleased with your Lord. He is also the Lord of your heart.
The chanting of the Hare Krishna mantra is recommended even for persons who commit offenses, because if they continue chanting they will gradually chant offenselessly.
Purport on Srimad Bhagavatam 6.3.24
One has to continue chanting the Hare Krishna mantra and preaching the chanting of this mantra because such preaching and chanting constitute the perfection of life.
Purport on Srimad Bhagavatam 4.24.67
Even if one distributes ten million cows in charity during an eclipse of the sun, lives at the confluence of the Ganges and Yamuna for millions of years, or gives a mountain of gold in sacrifice to the brahmanas, he does not earn even one hundredth part of the merit derived from chanting Hare Krishna.
If we chant and hear enthusiastically, then memory will come.