What should one do who abandons prayer despite knowing the punishment for abandoning it and experiencing temporary fear that soon dissipates?

The servant must offer sincere repentance and reclaim himself, for disobedience weakens the heart, deprives it of the will to repent, and exposes the servant to great danger. Indeed, the loss of abhorrence for sin and the absence of fear from it are among the greatest punishments for sins. Reflection upon death, the Day of Judgment, and Hellfire, sincere repentance, seeking Allah's help, accompanying righteous people, and striving against one's self are all essential for returning to the path of rectitude, for the door of repentance is open. Allah Almighty says: "And those who strive for Us - We will surely guide them to Our ways. And indeed, Allah is with the doers of good."