One piece of advice is to start with the biological side. Getting enough sleep, exercising regularly, and taking care of your physical health can have a surprisingly positive effect on your mental state.
At the same time, don't hesitate to seek help from a therapist. They can help guide the way you think about your experiences and how you interpret them. It's a gradual process, but it really can make a difference.
I believe you can get through this. :)
OP/reader, more specifically, examine that post. It is an avalanche of negative self-talk. It's a person telling themeselves and the world that they cannot do something. You can take a perfectly healthy person, turn on this cycle, and watch it destroy their lives.
Depression has many causes, but its roots that make it stick are cycles like these. Antidepressants are a parachute, but you have to rebuild the engine and an important part of that is to learn to reframe events and identify and challenge your negative assumptions.
I'd like to add that for certain kinds of people, the process of doing this on your own is near torture.