Karma (The four wives)

There was a man with four wives. He loved his fourth wife the most and took a great care of her and gave her the best.
He also loved his third wife and always wanted to show her off to his friends. However, he was always had a fear that she might runaway with some other man.
He loved his second wife too. Whenever he faced some problems, he always turned to his second wife and she would always help him out.
He did not love his first wife
though she loved him deeply, was very loyal to him and took great care of him. One day the man fell very ill and knew that he is going to die soon.
He told himself, "I have four wives with me. I will take one of them along with me when I die to keep company in my death."
Thus, he asked the fourth wife to die along with him and keep company. "No way!" she replied and walked away without another word.
He asked his third wife. She said "Life is so good over here. I'm going to remarry when you die".
He then asked his second wife. She said "I'm Sorry. I can't help you this time around. At the most I can only accompany you till your grave."
By now his heart sank and turned cold.
Then a voice called out: "I'll leave with you. I'll follow you no matter
where you go." the man looked up and there was his first wife. She was so skinny, almost like she suffered from malnutrition. Greatly grieved, the man said, "I should have taken much better care of you while I could have!"

Actually, we all have four wives in our lives.

a. The fourth wife is our body. No matter how much time and effort we
lavish in making it look good, it'll leave us when w die.

b. The third wife is our possessions, status and wealth. When we die, they
go to others.

c. the second wife is our family and friends. No matter how close they
had been there for us when we're alive, the furthest they can stay by us is
up to the grave.

d. the first wife is our soul, neglected in our pursuit of material
wealth and pleasure. It is actually the only thing that follows us wherever we go!

The Karma and life

Life is cruel because we have a flawed understanding of Karma. 

Good and bad karma do not cancel out each other. For good Karma you'll get good results and for bad Karma you have to suffer its consequences. Also, correlating Karma with time is futile primarily because nobody understands how it works. Besides, we have a limited vision and cannot realize which result is due to which particular (past) action.

Your Karma doesn't become good because you think so. A good karma is a deed which is done in accordance to your Dharma. Shri Krishna told Arjun during his pre-Mahabharata war dilemma that being Kshatriya Arjun's dharma was to protect people by fighting for righteousness. Hence all his killing were justified.

Bhishma Pitamah had the boon of dying at his own will, so he was lying on the bed of arrows till the moment the war did not end and he saw  Hastinapur in safe hands. Later when Krishna went to meet him with all Pandavas, after offering pranama,Bhishma asked him this Mrityuloka or Earth is the land of Karma and this is place where we receive the result or fruits of our past karmas. 

He said,"I know about all my past 100 births, but I never caused any pain to anyone, then why I have received so much pain through this bed of arrows?”

Listening to this question Krishna smiled and asked him,“You do remember all your past 100 births. What about the 101st?”, then Pitamah said,“I don’t remember about my 101st birth”. Krishna told him that “in your 101st birth you were a prince and committed a sin by throwing off a snake with your arrow, when you had thrown it away then it had fallen upon a place which was full of thrones, many thrones got pierced through the body of that snake, it was causing great pain to him, later all family members of that snake tried to help him to get rid of those thorns, but they failed, then before dying the snake cursed you “O King! I don’t know your identity, but the way you have caused me pain of thorns similarly one day you too will experience the same, you too will have a huge family, but no one will be able to uproot those thorns from your body and in this way you will die.”

Krishna added,“as you followed the path of devotion in all your births so it was protecting you till date from the sin you committed, but as now you have fought from the side of Adharma  so the dormant sin has ripened now.”. After listening to that Pitamah Bhishma was satisfied and he wished to die, then a divyajyoti (soul) came out of his body and found it’s place at the lotus feet of Shri Krishna. 

Karma acts for everyone. Nobody escapes from it.

Now this may sound humorous but I find a particular song Urvashi-take it easy to aid in such moments of frustration-bad people getting successful and we keep struggling. It says, for winning we need to follow "Take it easy" mantra. No matter what the result is, in spite of your continuous good effort, always take it easy.

On a serious note, Lord Krishna told Arjun 

कर्मण्येवाधिकारस्ते मा फलेषु कदाचन।
मा कर्मफलहेतुर्भूर्मा ते सङ्गोऽस्त्वकर्मणि॥

which means

You have the right to perform your actions,but you are not entitled to the fruits of the actions.
Do not let the fruit be the purpose of your actions, and therefore you won’t be attached to not doing your duty.

So stop worrying. Don't expect anything. Keep doing good Karma. We never know how it will pay off. But it sure would.