If you want to benefit from the Quraan, then gather your heart when you read and listen to it, pay close attention, and be [mentally] present as one would be if he were in the presence of the One who spoke it (??Allaah) Subhaanahu while he is speaking it (the Quraan), from Him [Allaah] to the slave. For indeed it is a speech from Him to you through the tongue of His messenger.
[Allaah] Ta'aala said:
"Verily, therein is indeed a reminder for him who has a heart or gives ear while he is heedful." [Qaaf/37]
And this is because: The complete effect [of the Quraan] will not occur unless the following are combined:
 Something which possesses the ability to give a strong effect;
 A place that is susceptible [for the effect to take place];
 A condition for the effect to take place is met;
 A barrier which obstructs the effect from taking place is removed.
And the [aforementioned] verse incorporated all of these in the shortest, clearest and most substantial phrase.
For His saying;
"Verily, therein is indeed a reminder..."
is a reference to what has already been mentioned from the beginning of the Suraah to this point, and this is what possesses the ability to give a strong effect (the Quraan).
"...for him who has a heart..."
This is the place which is susceptible for the effect to take place, and what is meant is: The heart which is alive, a heart which thinks and contemplates about Allaah. As [Allaah] Ta'aala said:
"This is only a Reminder and a plain Qur'aan. That he or it (Muhammad Sal-Allaahu 'alayhe Wa Sallam or the Qur'aan) may give warning to him who is living (a healthy minded the believer)..." [Ya-Seen/69-70]
Meaning: One who has a heart that is alive, and His saying:
"...or gives ear..."
Meaning: He concentrated and turned his sense of hearing to what is being said to him, and this is the condition that has to be met for the speech to have an effect.
"...while he is heedful."
Meaning that his heart is present and witnessing, not absent. Ibnu Qutaybah said:
"He listened to the book of Allaah, while his heart and mind were present, and he was not in a state of inattentiveness nor absentmindedness."
And this is the indication to the barrier which prevents the effect from taking place, and it is the absentmindedness of the heart and its absence from thinking, pondering and looking at what is being said to him.
So if there is something that has an effect, which is the Quraan, and a place for that effect to take place, which is the heart that is alive, and the condition is met, which is concentration, and the barrier is removed, which is the preoccupation of the heart and its absence from the meaning of what is being said to it, and its departure to something else, the effect will take place, and it is the benefit and the reminder.