Mechanics?

Warning:not an emotional post.

Have you ever wish that everything,(or not everything,your plans at least) to go accordingly to your whims and wants?

I make up stories.
Sometimes I write and make up those stories.And when you write a story,one of the best thing is that events and occurrences happen,(or at least persist to happen) according to you.
How the characters act,what consequences befall them,what come to them in the end--all these obey to your wishes.And the story do seem coherent,don't they?
Thus you(or maybe only me) think,if you can make a character,create events for it,lend it actions and see the character to the end, why doesn't this apply to real life.
In short,why doesn't life abide to plan,even after you consider all the circumstances involved?

The question above occurred to me.
So?
So one day as I was my doing my mechanics homework,it all seems clear to me.
The mechanics question was about a block on a platform tilted to a certain degree.
Friction prevents the block from sliding.
What is the degree for the platform to be tilted,so that the block slide?The friction constant is µ.
I'm sure most of A-level's students are familiar to this question.
The steps are to find the vertical weight component,times µ,which is equal to the horizontal weight component times Earth acceleration.And somehow from all this you will obtain the degree.

See, if in the real world you were asked ;Would it slide at 35°?,you can simply tilt it.
The answer would clearly be yes or no.
But the real mechanics as you see,is more complex.

So is life.
Let say if you do this,you would get this.However things aren't simple as it is,as there are many factors involved.Analogously,you have to know the µ,find vertical and horizontal component and bla bla bla.If the µ changes- a small rubble stuck between the two surfaces-,everything changes with it.
Would you care to calculate the degree again?
I myself would not.

Hence it was clear,if I cannot even calculate the answer to it, a small event in time(whether a block will slide or not),how can I foresee the future and outcome to my present actions?
So I thought,if things don't fall to places,
who am I to demand plans to flow smoothly?
I am only a simple human,a servant to the all-knowing.
Fumbled at elementary computations,
Humbled by own weakness,back to my sense.

Alhamdulillah.