A hHuge.

"Huge" in this case is an adjective, not a noun. And it can form a sentence all by itself.

I could spend a whole day thinking about a small task I haved to do and finding a lot of other activities (to do instead) before realizing the day was ending.

It reads better adding the additional phrase.

Some times, before going to bed, I wasould wondering about what I've had done that day, and I caouldn't figure it out.

Keep verb tenses consistent with each other. If one event is stated in the past, other events should also be stated in past tense.

I had a lot of stuff stalying everywhere in my place, like an old computer I wanted to fix, some cooking stuff, etc.

That was sometimes painful : I had to do some administrative tasks,. I wasould finishing some important thing during the night because it had to be done in the next morning,. I was stressed by this situation.

Avoid run-on sentences. This happens when two (or more, in this case) complete sentences appear as a single sentence, without proper conjunctions or punctuation.

I hated this, but I caouldn't help myself: I was procrastinating.

Okay, at this very moment I have just remembered the existence of LangCorrect and wanted to see if I canould write something interesting in English, in the middle of one or two other tasks.

I think the big difference in my life now is that now I do something only if I want it.

To say "big difference in my life" doesn't give us a reference to what other aspect of your life you're talking about. I moved "now" closer to make it clear that you are comparing your life in the present to that of your past.

And I want it because either it's like a game or something fun, or if I really need it.

"if" in this case is unnecessary and sounds awkward.

Some things doesn't fit with this new theory like, as I have some paperwork to do ...

In this case, I try to think of my future meself as a stranger to whom I will give all the things in my life.

And I'm asking myself : "If I wasere this stranger, what would I think about the fact that the current me didn't do this crap "?

"If I was this stranger" is okay for colloquial American English, but in writing it is incorrect. It's better to use the subjunctive: "If I were this stranger"

".

Maybe, my way of thinking has changed a bit.

It try to avoid to thinking too much, on about the long term, etc.

It helps me focus on the present activities and to lowers the emotional impact attached to it if I fail something.

"attached to it" is awkward because it's not clear what "it" refers to. The sentence is clearer with that phrase deleted.

There is also have been some changes in my life that help me to avoid procrastinating : I have no job, I live in a small place, I've disabled my phone notifications, and the news, I avoid to looking at the clock all the time, etc. etc.

etc.

I'm not sure it's relevant there ...

I'm not sure what you mean by this sentence. It seems completely unrelated to the rest of your essay.

Finally, maybe it's just that maybe procrastinating is now a harmless thing in my life ?