Everyone wants to achieve something in life. (Well... almost!) One studies all night to score well, the other runs a marathon to be the first to cross the ribbon, still others wake up early to go out to earn a living just to make ends meet. They all do things which would enhance their chances of getting closer to where they see themselves.
Lets take the example of CAT. There are a million factors which affect how one does in the exam. e.g. your temprament on that day, the test centre, the strictness and impartiality of the invigilators, the traffic, the interviewer's mood, the bugs in the question paper, the small set of questions which finally comes in the paper and your level of preparation. [of course, there are many factors, but that's not the focus of this post!] Out of these things, the only thing which you can control is your level of preparation. Isn't it strange, that out of the gazillion things that can make a difference, you have control over only one factor? Doesn't that make you feel that there is alot of randomness and again, (I hate to say it! but....) alot depends on luck!
Serious CAT aspirants work on the ONE factor that they can control- their level of preparation. Imagine a case where none of the students were to study for CAT then all the students appearing would be at the same bar. There would not be any solid distinction to be made between the students. Meaning, all the aspirants were equally likely to make it to the IIM of their choice. That's randomness!
So in order to tip the scales in their favour, students study and those who prepare better reduce the amount of randomness affecting their outcome. Similarly all the ambitious people mentioned in the first para of this post, and in fact, each and every person who lifts even a finger with an aim in mind, does so to reduce the randomness. So basically, all that we do in life, I mean ALL the things that we do in a focussed manner, help us reduce randomness [as opposed to just sitting on your a**].
As the second law of thermodynamics says : "the entropy of an isolated system which is not in equilibrium will tend to increase over time" and it is upto us (and our actions) to reduce that.