The importance of hard work

I think that hard work is the most important thing to succeed. In fact, there is no success without hard work. Why? Because working hard allows you to practise more, and this means that you can become an expert about in a particular discipline.

Since you are in the USA, you should know that practise is perfect British English but in America you should write practice. You can also be an expert on something or an expert something, but you cannot be an expert about anything. So you can be an expert on biochemistry, a biochemistry expert but not an expert about biochemistry.

Hard work means that you have to spend a lot of time before mastering something. This also means that you will face failure; you will sometimes feel stuck, and tempted to give it up. Success has a high price. But being successful also means distinguishing yourself by other people, and even doing do what others hate doing. It means doing something even if you're tired, bored, and unwilling.

British: "tired, bored and unwilling", and American exactly as you wrote.

Because habits are more important than sporadic actions, and "success it's not a final destination, rather it's a journey" like as someone also once said. Working hard is the only way to achieve it,; there are no shortcuts, and no other solutions. I also think that luck doesn't exist, but. Instead, we are what we do every day. In fact, if you think of who you are, what could you say? Probably, you will say that you are that thing that you repeat more often in your life.

You will probably say that you are the product of the things that you repeat most often in life.

For instance, if you like running and go running daily, you are a runner. If you like painting, and do it many times, you are a painter. If you like writing and do it every day, you are a writer, and so on. Actions that we repeat can make ourselves us. Hard work also means also repeating a particular action (or sequence of actions) many times, until you become damn good at doing it.

I'm not sure but, in America, I think that "damn good at" is okay. I think in British English we would write "damned good at".

And this means improving your skills, which means success.

Okay but maybe "This improves your skills and guarantees success.".