How often do we feel we have a special right to be irritated, frustrated, or any number of responses sinful simply because of a physical, mental, etc. malady. "It's that time of the month therefore I'm excused for my irritable responses to others".  "My tire is flat so I can be angry at the people who won't stop to help or even slow down". Or in my case "I'm having a bad depression day so I am entitled to a pity party, a free pass from consistent child-training, from serving others and especially from rejoicing always..." Believe me, I have quite the repertoire of "excuses" from obedience that have the reason of being a result of God's allowing difficulties and illness in me. 

We are not absconded from responsibility for our sin because God has allowed something in our life that makes it difficult to obey.  Maybe I can remember to view these times when obedience is made much more difficult by circumstances as "muscle-building", increasing my strength in relying on God's grace so maybe it will be more instinctual the next time.