Courage is such a thing created by Allah that it enables a man, Muslim or non-Muslim, to accomplish exceptional feats and Allah blesses his efforts. Allah will certainly bless the courage of a believer who works hard to submit to Him and avert disobedience. Allah has blessed the quality of courage with exceptional power so that great things can be achieved with firm resolve.
The tasks that a person is asked to do are within his ability. He only has to show courage. One has to courageously show obedience and keep away from sin. One has to spend one's whole life doing it and if there ever is a slip, he must courageously renew his efforts. It is through courage that man moves forward but without courage he can do nothing in the world. Only courage enables him to do everything.
The method to correct deeds and inner condition is to oppose the sentiments of the nafs(lower self) and accustom it to hard work. The more you accustom it to hard work, the more it responds and you will get your work done, inshaAllah. As a result, the apparent deeds will be corrected and the unseen character will also be reformed.
[Spiritual Discourses by Mufti Muhammad Taqi Usmani Sahab]
Taken from Here