Consequences vs. Grace

As I spent two hours of my day on a train or waiting for a train, I have loads of time to think and feel and ponder. Today I thought about the mistakes we make in life and the consequences of those mistakes. I'm wondering if the 'innocent' mistakes we make have short lived consequences...like one can change a job if you feel you made the wrong decision or if you uploaded the incorrect file you can go back and correct it. My question is, when you make a mistake that Scripture call sin, how long do you have to face the consequences of that act? And how does forgiveness and grace fit into it all? To my understanding asking for forgiveness means 'He is faithful and just and will forgive you and cleanse you of all unrighteousness' 1 John 1:9...but consequences still follow. Are consequences of sin long lasting, or does God keep it in your life untill you have learnt the lesson needing to be learnt or you have truly and sincerely humbled yourself?