What is the most important thing that you have learnted in all your life?

I think "learned" is more correct. :-)

Something that I have learnted recently, it's that we must live without regrets as much as possible.

Optionally, "we must live with as few regrets as possible." I actually think that's better. ... "without regrets as much as possible" _works_, it just feels off.

I've heard about people who wanted to express how they felt but never did, and now they lived with sadness and depression thinking about, "what would have happened if I had expressed how I felt or if I had tried this?

* Es una frase muy larga, y entonces es mejor utilizar una coma (",") para separar las cláusulas, y para dejar espacio para que sus lectores puedan respirar. :-)
* "wanted" ... "lived" = concordancia de tiempos. También puedes escribir "and now they live" como hiciste.
* thinking, "xxxx" -- se usa la coma para separar el verbo (thinking or saying) del contenido. Me explico? :-P

As long as the thing that you want to do doesn't affect or damagehurt someone, go ahead.

* "hurt someone" es más común.

Something that I have learnt recently, it's that we must live without regrets as much as possible.

I've heard about people who wanted to express how they felt but never did and now they live with sadness and depression thinking about "wWhat would have happened if I had expressed how I felt or if I had tried this?

".

そうですね。

What is the most important thing that you have learnted in all your life?

Something that I have learnt recently, it's that we must live without regrets as possible.

I've heard about people who wanted to express how they felt, but never did and n. Now they live with sadness and depression, thinking about; "wWhat would have happened if I had expressed how I felt or if I had tried this?

Something that I have learnt recently, it's that we must live without regrets as much as possible.

I've heard about people who wanted to express how they felt but never did and now, they live with sadness and depression, thinking about "what would have happened if I had expressed how I felt or if I had tried this?"

As long as the thing that you want to do doesn't affect or damage someone else, go ahead.

It's better to try and fail, than never to have triednever tried at all.

What is the most important thing that you have learnted in all your life?

“In all your life” is correct but “in your life” would sound better.

Something that I have learnted recently, it's that we must live without regrets as much as possible.

As long as the thing that you want to do doesn't affect or damagehurt someone, go ahead.

Something that I have learnt recently, it's that we must live without regrets as much as possible.

In the US: “learned”

Sometimes we canmay be afraid or worried about taking risks.

I've heard aboutof people who wanted to express how they felt but never did and now they live with sadness and depression thinking about "what would have happened if I had expressed how I felt or if I had tried this?

As long as the thing that you want to do doesn't affect or damagehurt someone, go ahead.

“Damage”: things
“Hurt”: people