Is optimism about entering Paradise, despite shortcomings and sins, considered a sin, or is it permissible?

Having a good opinion of Allah Almighty is legally required at all times, based on the Prophet's (peace be upon him) saying: "Allah Almighty says: I am as My servant thinks of Me." This, however, does not mean becoming lazy in acts of obedience, relying solely on Allah's mercy, for this is a form of feeling secure from Allah's plan, which leads to loss. Allah Almighty says: "Did they then feel secure from the plan of Allah? But no one feels secure from the plan of Allah except the losing people." The righteousness of a believer is achieved by combining fear and hope, balancing them during times of health, and letting fear predominate to increase good deeds. Hope should predominate in times of weakness or when death is near, to increase one's dependence on Allah. The righteous predecessors combined intense fear and hope when death approached.