Does the feeling of tranquility when reciting the Quran result from contemplation, focus, and reverence, or does the reciter attain it even if heedless and unmindful? And how does a Muslim achieve tranquility and peace of mind from reciting the Quran?

Tranquility of the heart is achieved through the remembrance of Allah, and the best remembrance is the recitation of the Holy Quran. Humility and serenity may be attained through reciting or listening to the Quran, even for those who do not understand its meaning, for there is goodness and blessing in its recitation. One who recites the Quran without contemplating its meaning is not like one who has not recited it at all, but they receive less good. Whoever desires tranquility of heart and peace of mind must engage in the remembrance of Allah generally, and the recitation of the Quran specifically, while contemplating its meanings and applying its rulings.