Please check my sentences grammatically (7.7 (1))

I worked out at the gym in the at night. Sometimes I feel burdened when I go to work. It is stressful but I think if I want to improve myself, I have to get have this burden. In korea, there is a limition retirement a working age limit. That is "60 years old". On tThese days there are not many people who retire when they are 60 years old. In my case, maybe I will retire when I am 40, 50years old. Unfortunately, human life is longer than before, almost 100 years old! That's why 50 years old means, that is just half of my all life. I would already retire. That is awful! I will quit my job when I am at least 35 years old. I want to do own my job. If I retire, I want not to be worried about money. I don't any plan to go another company. Some days, I want to do other work for my career. It is important to get a variety of experiences. I think Korea does not use common sense. There are so many secretive actions, like getting [a bribe]/[bribery]. Korea looks like a good nation for only the rich. I have to overcome Racism in America.