You have to pay back all Karmas in this life or in future lives, good or bad. It could be good Karma, but if it is selfish it is a chain that binds you. Nishkam Karma also still binds you to the Karmic law. It doesn't matter if the chain is made of iron or gold, it binds you in same way. Good and bad, both Karmas will bind you, put you into bondage. Of course negative Karma is harder, and good Karmas are softer.
Nishkam Karma means free or without desire. Karma comes from the root word “kama” which means desires. Karma comes from the root word "kriya" which means to do. In the act of Nishkam Karma you have no selfish expectation, you are only giving. Give with love, devotion and happiness. What should we give? Whatever you can! But observe your limitations, don’t overdo it!
Nishkam Karma means doing Seva (selfless service), without the expectation of receiving acknowledgement, reward or a word of thanks. When you have even just one thought that someone should have said "Thank you", this is not Nishkam Karma. In Vedic culture there is no tradition of saying 'Thank you', only 'Blessing'.
This can be a problem for westerners when they go to India, that whatever you may do, Indians will never say thank you. But with modern education the word thank you has spread everywhere. However, when you say thank you, it means you don’t accept this Seva and you give back some fruits. Nishkam Karma leads to liberation.
Selfless service bears fruit similar to Raja Yoga, Bhakti Yoga and Gyana Yoga. The fruits of Sakam Karma will be paid for in this life and the fruit of Nishkam Karma will be returned after this life. Here you enjoy a life of luxury, but in another life you will have empty hands. What will go with you? Don’t just think of this life, think also of your future lives. Therefore, in Yoga and Indian culture there is less focus on past lives, but more on future lives.
Past is past, you no longer have any control over it. In a past life you were king and now you are a cook. Suddenly you gain knowledge of the past life when you were a king but nobody will give your kingdom back to you, instead you will be taken to a psychiatric hospital.
So, what do you get from the past? Do something for your future. Or do something for a permanent position - immortality. That’s what Mahaprabhuji has spoken in his bhajan: Guruvara Me Calu Sa Una Des….
The translation of this Bhajan is :
Gurudev please let me join You in Your highest world.
What other people are saying doesn't matter
Full of Vairagya I only want to follow You
In that world there is neither birth nor death
Nor Karma, nor effects
In that world one becomes Jivanmukta and gains the highest bliss
In that world there is everlasting light
There is neither moon nor sun, nor colours nor form
Oh Lord, neither a King nor a begger can reach that world without Your mercy
That world is the dwelling place of all Holy people
My adoration to them
There is flowing the nectar of your wisdom, Oh Gurudev
Sri Deep Mahaprabhuji says
I am longing to be there where one will never be born again