How can one truly attain reliance upon Allah? What are the conditions and impediments of reliance upon Allah? And what should a person do if they are unable to mentally achieve reliance upon Allah?

Reliance upon Allah is based on the knowledge that all matters are in His hands, glory be to Him; He is the sole Disposer of affairs. And whoever knows this truth will find it easy to entrust all matters to Allah. Reliance does not negate taking means (i.e., making an effort), rather taking them is part of the perfection of reliance. Therefore, a Muslim should entrust his affairs to Allah with his heart, while his limbs are engaged in lawful means. The condition for reliance is sincerity to Allah and entrusting matters to Him, along with taking means. Its impediments are: attaching one's heart to the means, or believing that benefit and harm occur without reliance on and entrusting matters to Allah.