This messagetext is going to be short, because the topic is more difficult then just talking about daily stuffs.

Or "will be short"

N(Right) now, I'm reading a psychologicy book which callsed "The New Mood Therapy".

Or "which is called", but called alone is more natural

I have started to read this book because I got noticed how fast and sharply my mood changes.

To me, "I had started" implies the starting came first, and then you noticed the mood changes.

TheOur thoughts can be false if they wasere build upt on our negative convicperceptions.

Usually, our negative convicperceptions are wrong and they don't connect with our reality.

So there is a simple process - we had got some negative convictionthoughts in the past (like 'everyone hates me' or 'I will never find thea partner'), then some situation happens in our present and we estimateinterpret it basinged on our past experience and using our negative conviperspectionve.

We don't analyze our present situation, we just use our past pattern.

And the questions is w, "Which type of feelings we cando we get basinged on our negative convicperceptions?"

Obviously, it will be negative.

So, if we don't work out withn our negative convicperceptions, we will often feel sad and negative emotions.

work out = plan with intention
work on = spend time improving

As far as I concernedunderstand, analyzing and controlling our thoughts is the key to be happy and calm, and I couldn't agree more.

If you use "As far as I'm concerned," that would be correct but it would make the "and I couldn't agree more" irrelevant, since "As far as I'm concerned" signals your opinion.

This message is going to be short, because the topic is more difficult thean just talking about daily stuffs.

then = after something.
than = comparing two things. A vs B

Now I'm reading psychological book which callsed "The New Mood Therapy".

I have started to read this book because I got noticed how fast and sharply my mood changes.

Do not need "have" or "got" as "started" and "noticed" are the action/verb.
"-ly" (e.g. sharply) is usually used to describe a verb. In this case, "fast and sharp" describes "mood" which is a noun. Therefore, do not need "-ly".

According the book, we should distinguish our thoughts and our reality.

The thoughts can be false if they wasere build up on our negative convictions.

was = one/singular, were = more than one/plural/multiple. Since item is "thoughts" with an "s", therefore, it is plural.

So there is a simple process - we had. We got some negative conviction in the past (like 'everyone hates me' or 'I will never find the partner') t. Then some situation happens in our present and we estimate it basinged on our past experience and using negative conviction.

Made it into separate sentences to prevent run-on sentences. It is easier to read and flows better.

We don't analyze our present situation, we just use our past pattern.

And the questions is which type of feelings we can get basinged on our negative convictions?

As far as I am concerned analyzing and controlling our thoughts is the key to be happy and calm, and I couldn't agree more.

And you?How about you? (or What do you think?).

"And you?" is not incorrect. But sounds a bit impolite and very direct, especially in writing.