Jesus said “pay attention to the word you hear.” That doesn’t mean listen really hard, that means attend to it. If you have a garden, you don’t pay attention to it by looking at it, you get your hands dirty by tilling the soil, watering the seeds, eradicating pests and uprooting invasive plant species.
“Paying attention” to the word of God that you plant in your heart means you need to make sure you’re watering it. Stay in faith. Make sure you are thinking how God thinks about your life. Pray and meditate, include God’s logic in your thought processes. Change the way you’re thinking about your circumstances and see God’s possibilities and promises.
Paying attention has more to do with the meditation of your heart than the function of your ears or eyes.
From Expositor’s Greek Testament
There shall be given over and above, not to those who hear (T. R., τοῖς ἀκούουσιν), but to those who think on what they hear. This thought introduces Mark 4:25, which, in this connection, means: the more a man thinks the more he will understand, and the less a man thinks the less his power of understanding will become. “Whoso hath attention, knowledge will be given to him, and from him who hath not, the seed of knowledge will be taken. For as diligence causes that seed to grow, negligence destroys it,” Euthy.