I started dancing in this summer. I started dancing this summer.

It's very good to do exercise, especially in these times, due to covid 19. It's very good to do exercise, especially in these times, due to covid 19.

especially, not specially (native speakers make this mistake too hahaha)

It's very good (mejor: healthy, beneficial) to do exercise, especially during these times, due to covid COVID-19. It's very good (mejor: healthy, beneficial) to do exercise, especially during these times, due to COVID-19.

However, it was so hard to do it well, like languages,. I thought I was doing it right but when I saw how it was and saw all of my mistakes I was so embarrassed. However, it was so hard to do it well, like languages. I thought I was doing it right but when I saw how it was and saw all of my mistakes I was so embarrassed.

I think it would be better to find a way to split this sentence in two so it isn't a run-on.

However, it was so hard to do it well,master it, just like languages,. I thought I was doing it right, but when I saw how it was and allactually was supposed to be done and when I took note of mythe mistakes I wasthat I made, I felt so embarrassed. However, it was so hard to master it, just like languages. I thought I was doing it right, but when I saw how it actually was supposed to be done and when I took note of the mistakes that I made, I felt so embarrassed.

So I did it over and over again and now I think I became better but there's are a lot of things that I need to improve yet. So I did it over and over again and now I think I became better but there are a lot of things that I need to improve yet.

things is plural, so 'are' instead of 'is'

So I did it over and over again, and now I think I becameam much better, but there's are still a lot of things that I need to improve yeton. So I did it over and over again, and now I think I am much better, but there are still a lot of things that I need to improve on.

You see, people stay in their homes without moving and that's bad for the body,. "wWhat you don't use will degenerate," they say. You see, people stay in their homes without moving and that's bad for the body. "What you don't use will degenerate," they say.

Just some small punctuation changes to make it seem less like a run-on sentence.

You see, people stay in their homes without movingand laze around, and that's bad for the body,. "wWhat you don't use will degenerate," they say. You see, people stay in their homes and laze around, and that's bad for the body. "What you don't use will degenerate," they say.