Here's a version that uses vocab that a native speaker would be more likely to use (IMHO): I lay down on the green grass far into the night, taking in a view of the night sky so wonderful that nobody could ever imagine how beautiful it was. Suddenly I realized how lucky and happy I was to be able to enjoy such amazing opportunities to travel in my life. I decided that I was really dealing with a lot of unnecessary anxiety about things that I don't really have to do; about things that don't really matter. I was trying to resolve this struggle in my head, but nothing came to me. I'm still trying to figure out how to be happier, and how to not deal with all of this useless anxiety, even if it takes ("even if it were to take" is better English) me a couple of years to make it happen. If I were to answer my own question, I would say that there is only one way to do it. It would be by spending my precious summer vacation time traveling to places I'd like to go to, and by having a sunnier view of life.

Both are interesting, but the phrase 'I lay down' is the correct one, whereas the first reads more smoothly.

JoAnNey has a great response. Here is just another: Far into the night, I lay down on the green grass watching a wonderful view of the night’s sky. No one can imagine how beautiful it is. I suddenly realize how happy and lucky I am to enjoy such an amazing travel in my life. And I thought, I was so struggled with my anxiety of what I don’t need to do, I still do not have an answer. I am still looking for the better answer on how avert from useless anxiety to be happier, now, and even two years from now. I would say the only answer is to travel. I want to travel on my precious summer vacation and take a cheerful view of life.

I laid down on the green grass while watching the wonderful view of the night sky. Nobody can ever imagine how beautiful it was. Then I suddenly realized how lucky and happy I am to enjoy such an amazing travel in my life. And I thought I was really struggling with my anxiety of what I don't need to do. but there was no answer. and I am still looking for a better answer on how to avert myself from useless anxiety to a happier state, even if it would take me 2 years to do so. if I answer my question, I would say that there is only one way to do it. it would be traveling somewhere I want, to spend my precious summer vacation or having a cheerful view of life.