Will Allah accept the repentance of one who was unable to endure affliction previously, but has now resolved to endure it for the remainder of his life?

If you become impatient and discontent with Allah's decree, and you commit what is impermissible, thereby contradicting the obligatory patience, then you must perform sincere repentance and feel remorse for your shortcomings. For Allah is Oft-Forgiving, Most Merciful; He accepts repentance and pardons evil deeds, and one who repents from a sin is like one who has no sin. And if your repentance is sincere and the affliction persists, then your patience with it will be weighed in your favor and you will be rewarded for it.