1 Don't change anything about yourself, you are good enough. <-- anything. A typo, I think. 2 Stop pretending to be happy, we know you are depressed. <-- great. They seem separate sentences, so I'd use a full stop (period) or another choice of stop where you use a comma. 3 Will the boss pay us for the overwork? <-- overtime? overworking has the feeling of doing more than asked. overtime has the feeling of working longer because it is expected or required (May vary from place to pl;ace) 4 I regret being born in my country. <-- great 5 I am so sick of the people who I work with. <-- maybe this should be whom? But regardless "I am so sick of the people I work with." sounds more natural to me.

5a. I am so sick and tired of the people with whom I work. 5b. I am so sick and tired of the people whom I work with. 5c. I am so sick and tired of the people who I work with. 5d. I am so sick and tired of the people I work with. 5a and 5b would make your teacher proud of you, for you have used whoM" correctly. 5c and 5d are very natural. As Nanren said, many native speakers (here in the United States) would probably choose 5d.