How can a Muslim become a devout worshipper, an ascetic, and a martyr, while living in a land of disbelief, having forgotten the Quran, suffering from psychological illnesses and lethargy, and fearing that his current state is not considered repentance?

Firstly, you must strive to seek treatment for the psychological illness that has afflicted you.

Secondly, there is no sin upon you for forgetting the Quran as long as it was not by your choice or will, but rather stemmed from your illness.

Thirdly, we advise you to strive against your ego and endeavor to review the Quran, with persistence and determination to overcome this illness.

Fourthly, have good thoughts about Allah Almighty, and seek help through abundant supplication and entreaty to Him.

Fifthly, know that you will be rewarded for your good intention for the good that your illness prevents you from, based on the hadith: "Whoever sincerely asks Allah for martyrdom, Allah will grant him the stations of the martyrs, even if he dies on his bed."

Sixthly, strive to perform whatever acts of worship you are able to, and exert yourself until you are cured, seeking assistance by consulting trustworthy doctors.