Yesterday was my last day at my job.
Why did you quit your job?
The work pressure was ridiculous and I couldn't concentrate on my task anymore. I had my mind on something else most of the time.
It sounds like you made the right decision. You shouldn't have stayed in a job that you didn't like and that you couldn't give the proper attention to. Hopefully you will find a job that is a better fit for yourself.
What if I said now that I'm depressed about it all though?
Depression is not good, see a therapist right away. You didn't need to stay at a job that you hated either. Things will fall back into place eventually for you.