I don't understand why I prefer a difficult tasks instead of common job.

"common" and "difficult" are not exactly contrasting, so this sentence sounds a bit odd.

The mMost people in my country just want to be a simple programmers without challenges and continuous professional development.

All of the study program oin our department was built on the web-stack — it was in demand in my country.

Of course I was driven, and "made lemonade" of the lemons which life gave me.

I concentrated on math and an algorithms.

Math has given me a better path in lifeway than if I had just been a web coder.

"lifeway" isn't a word.

Currently, I have time and good chance to get the perfect high education in Computer Science (because I have money and experience, I got them while I job instead of a getting a high education).

What is "high education?" Does this mean graduating with good grades?

That's the reason why I learnpractice English so intensely.

Practice makes more sense here, to really emphasize that it is hard work and toilsome.

I don't understand why I prefer a difficult tasks instead of common jobs.

The mMost people in my country just want to be a simple basic programmers without any challenges and without continuous professional development.

All of thThe entire study program oin our department was built on the web-stack — it was in demand in my country.

Of course I was driven, and "made lemonade" ofwith the lemons which life gave me.

I concentrated on math and an algorithms.

Math has given me a better lifeway path than if I had just been a web coder.

Currently, I have the time, and good a chance to get the perfect higher education in Computer Science (because I have money and experience, I got them while I jobworked instead of a getting a higher education).

Although I can just study at the best University in Belarus/Russia, I want to geto for more.

That's the reason why I learn English so intense.at such an intense pace / That's the reason I study English so intensely / That's the reason I go so intense with English

That's wWhy I learn English

I don't understand why I prefer a difficult tasks instead of common job.

"a" would be used if the phrase following it were singular, but "tasks" is plural

The mostMost of the people in my country just want to be a simple programmers without challenges and continuous professional development.

- Use "of" to describe that you are talking about "a part" of the people of your country. in this case "the part" is "most" of the country

All of the study program os in our department was built on the web-stack — it was in demand in my country.

"in" instead of "on" since we are talking about the programs that you department has (the programs within the department"

Of course I was driven, and "made lemonade" ofut of the lemons whichthat life gave me.

Commonly we don't use this sentence structure when talking about the common idiom "when life gives you lemons, make lemonade." But grammatically, its correct.

I concentrated on math and aon algorithms.

Would use "an" if it was a singular algorithm.

Math has given me a better path in lifeway than if I had just been a web coder.

Lifeway is not a word we use in english. I wrote an option for what I think you were trying to say?

Currently, I have time and a good chance to get the perfect high education in Computer Science (because I have money and experience, which I got them while Ibecause I got a job instead of a getting a higher education).

- Instead of "chance", the word "opportunity" might be better here
- Do you mean higher education (like a college degree) or a level of education that is prestigious/high quality?
- If its prestige --> I have time and a good opportunity to receive a prestigious education in Computer science.

Although I can just study at the best University in Belarus/Russia, I want to get more.

That's the reason why I learn English so intensely.

Intensely is an adverb describing the verb learn (adverbs describe verbs)