No, it is not deja vu. I have not had it before. Neither had the others. It is simply the thumb rule of reciprocity. What goes around comes around. But that is that. Newton's third law of motion also applies here. What you do is what you will get in return- as a consequence, it depends on how you get it started.. This is rather conceptual, I know but I am not going to include even one solid example about it. I have many. I believe many people, too. But just think of this and relate it if what we have in our daily challenging life. The survival of the fittest by Darwin, if there's a truth about it, has nothing to do with evolution and should not be the way we see it (though that is what it conventionally all about-the theory of evolution). Instead, to be the fittest, and therefore survive, we must understand this law deduced by Allah the Almighty God. Taking this on a deeper level, we in Islam however believe that patience must always come along the way. In a best-seller book of La Tahzan (Arabic words for Don't Be Sad), the author clearly explained how we may come across with people who wrote something bad about us using a qalam (pen or pencil) we sincerely bought for them! Err, so what goes around now, do not come around?
The truth is, if we are patient, then it is Allah's merit that we get in return, and the guilty will be punished by Allah with due consequence- and now our rules stand back ;) However, in today's era, it is not so us to just be patient and do nothing about it- at least a piece of advice would do, if we don't go for a more radical action :P
People also like to relate the occurence in life with Qada' and Qadar (Divine Will and Decree) of Allah- which is good, because that way, we actually associate everything to Allah and therefore (by right) surrender to his Willingness and the fact that He has the power in every single thing. One note though. It is more appropriate if we associate Qada' and Qadar with sunnatullah (Law of Allah) rather than destiny. They might be the same to a certain extent, but let me further elaborate on the way we should look at it.
If we take it as a destiny, then we tend to have lack of effort and sometimes motivation to achieve good things in life. Why? Well, because it's destined to be that way, isn't it? So, what's the point of trying so hard? Live with this principle- then success will always be at bay. Worst, we may eventually question Allah- Why did you make me like this? Why do you make this as my destiny? Ah huh? Seriosly? Do we dare question Allah, the All-Knowing? That's why, we just have to look at things from a better point of view. Sunnatullah. It is very simple. You do more, you gain more. No pain, no gain, so cliché right? Everyone has heard of the quote ;) But that is the whole point. We must strive our best and always go for an aim with greatest attempt and effort so that what we acquire at the end of it is well worth it. No short cut to success, yes you're right. I was thinking about that too. :) So, let us have a paradigm shift, today if we haven't, to admit that Allah has right in every single thing He does. Despite this though, praise be upon Allah a lot, because we mankind was created in the best way that He still granted us the free will to believe in Him, and also to decide what kind of life we want to live with. So my dear brothers and sisters, let's go make some colors on our fabric of life today and pray to Him a lot. Insya Allah wallahuaklam, He surely knows better.
P/S: Some simple explanation about Qada' and Qadar here.