aAbout study

You could also say "About studying", if you are discussing the act of studying rather than the noun of study.

Since I was a child, my parents taught me how important is to study and work hard to build a good and brilliant future.

This is a really nice sentence!

But beHowever, being a hard working person is tough, because either we start to be mean withto ourselfves, or we are already living in youra bright future oin our minds and hearts, and we simply forget to be grateful to handle with today´'s perils and to cheer on our little victories.

Depending on what you mean, you could say "simply forget to be grateful so we can handle today's perils", or "simply forget to be grateful of how we handle today's perils", or "simply forget to be grateful for handling today's perils".

You could also say "the day's" rather than "today's" to be more general.

Since I was a child my parents taught me of how important is to study and work hard to build a good and brilliant future.

But be a hard working person is tough, because we start to be mean with ourself or we are already living in your bright future on our minds and heart, and we simply forget to be grateful to handle with today´s perils and to cheer our little victories.

aAbout studying

Since I was a child my parents taught me how important it is to study and work hard to build a good and brilliant future.

But being a hard working person is tough, because we start to be mean with ourselfves or we are already living in youra bright future on our minds and heart, and we simply forget to be grateful towhen handle with today´sing daily perils and to cheer for our little victories.

aAbout sStudying

SinceWhen I was a child my parents taught me how important it is to study and work hard to build a good and brilliant future.

"Since" is something I'd use to describe something on-going, not a one-time event. For example: "Since 2015, she's been teaching me French." "I've been sick since last week, and this cough just won't go away!"

If you're parents are STILL teaching you to this day: "Since I was a child my parents HAVE BEEN TEACHING me how important..."

But being a hard working person is tough, because we start to bebeing mean withto ourselfves or we a're already living in youra bright future oin our minds and heart, and we simply forget to be grateful tso we can handle with today´s perils, and to cheercelebrate our little victories.

I don't understand what you mean by "we are already living in your bright future". In particular, I'm confused by the use of "your".

It's not incorrect to not use contractions like "we're", "you're", "I'm", etc; but most of the time, it can make things sound a lot more natural.

"Cheer", to me, is a very particular action. I cheer for someone at a sports match. Or I cheer someone on in a race as they cross the finish line. "Cheer" is exclusively an outward action, but "celebrate" can be inward.

I think we learn and grow more inthrough the process, and we can celebrate our victories in the process, not just when we achieve our goals.

"through the process" sounds a little more natural than "in the process" specifically in the first part, but it's very difficult for me to explain why. For now, just know that both should work fine.