The relationship between productivity and sin can easily be linked for any believer to explore. When a person commits a sin, he feels uncomfortable, uneasy with himself, and embarassed of his Lord. His mind is all over the place and is unable to think clearly because the thought that he has ruined his relationship with Allah disturbs him. This feeling of guilt and regret coupled with a confused sense of purpose will definitely have an adverse effect on a person's lifestyle, never mind his productivity.
A pious man once said "I can see the effect of my sin on my family and transport".
The flip side of the above, is that the door of forgiveness is open, and a believer can relieve himself of his sin by admitting it to his Lord, and beg for Allah's forgiveness. You can regain your focus in life, get back on the straight path after deviating from it, and continue on your productive life by Istighfar and repentance. It is easy, but unfortunately, here's where most people fail.
Sometimes shaytaan trick us by making us believe that our sin is too great to be forgiven, or that we don't know how to ask for forgiveness properly and hence won't be forgiven, we forget the famous hadeeth qudusi which says:
"O son of Adam, as long as you call upon Me and put your hope in Me, I have forgiven you for what you have done and I do not mind. O son of Adam, if your sins were to reach the clouds of the sky and then you would seek My forgiveness, I would forgive you. O son of Adam, if you were to come to Me with sins that are close to filling the earth and then you would meet Me without ascribing any partners with Me, I would certainly bring to you forgiveness close to filling it."
Or the verse of the Quran that says: Say: "O my Servants who have transgressed against their souls! Despair not of the Mercy of Allah. for Allah forgives all sins: for He is Oft-Forgiving, Most Merciful.
It takes emaan to ask Allah for forgiveness, and it takes yaqeen (certainty in Allah) to believe in Allah's forgiveness and be sure of it, but that also needs to be balanced with "khashya" a reverence of Allah that keeps the believer always alert and never take things for granted.
But here's the punchline of this article, if you want to boost your productivity (regardless whether you've just sinned or not) keep asking Allah for forgiveness! Keep saying "Astaghfirullah" or "la ilaha illa anta subhanaka inni kuntu min al-thalimeen" (O Allah, there's no god but thee, and I'm one of the transgressors"
Allah says in the Quran: "Ask forgiveness from your Lord; for He is Oft-Forgiving; He will send rain to you in abundance; 'Give you increase in wealth and sons; and bestow on you gardens and bestow on you rivers (of flowing water)"
The scholars of Islam knew of this secret and used it to help them in their everyday life, Ibn Taymiyya once said: "If I got stuck on a problem, I seek Allah's forgiveness 1000 times until Allah opens an answer for me".
This is a major topic, one that can be dwelled upon for many posts to come, but if I were to boil down one of the major secrets of being a Productive Muslim, it'll be Istighfar, Istighfar, Istighfar all the time.
Seek forgiveness of your Lord, let your tongue be wet by asking Allah for forgiveness, and watch how the bounties of Allah are bestowed upon you and your worries taken care of.
It works!! try it!