How can one get rid of the habit of looking at young foreign men and repent from it, despite being committed to acts of worship and feeling guilty?

A gaze is an arrow from the arrows of Iblis, and most immoralities begin with a look. Therefore, Allah and His Messenger commanded lowering the gaze. It is obligatory to make sincere repentance and to refrain from repeating the reciprocal gazes between a man and a woman, because it is the first step of Shaytan. The best means to protect one's chastity is marriage to a righteous man.