Are the fears and self-reproach concerning the torment of the grave, Paradise and Hellfire, and shortcomings in acts of worship, a sign of earnest adherence to religion and faith, or are they satanic whisperings?

Remembering death, the grave, Paradise, and Hell is praiseworthy if it results in increased acts of obedience and avoidance of disobedience, bringing peace to the soul and tranquility to the heart. However, if it leads to anxiety and disturbance, then it is a satanic whispering that causes laziness in performing acts of worship, boldness in committing sins, and despair of Allah's mercy. Therefore, one must close the doors to Satan and make these remembrances a path to Allah's obedience and the soul's happiness.