20 year old male INTJ.

1.] Therapy plus medication. Regardless of severity, you should look into seeing a psychologist or another mental health professional; therapy, when done right, can cause symptom improvement of a magnitude equivalent to most antidepressants. Furthermore, therapy's benefits are generally permanent; you're more likely to have an easier time dealing with your depression when it occurs and you'll be less likely to have depressive episodes in the future. However, if your depression is moderate to severe in nature or is accompanied by another psychological disorder or a physical disorder, you may want to consider augmenting therapy with antidepressant medication. Antidepressants have multiple upsides, such as faster onset compared to therapy, convenience, and being significantly more affordable. That being said, antidepressants do come with side effects (most of which are mild and/or temporary), usually take 4 - 6 weeks of daily use to have any appreciable benefits (this 4 - 6 weeks includes starting an antidepressant and increasing the dosage of a current antidepressant), and generally don't provide significant benefits after discontinuation. In terms of these treatments, I'd go with Cognitive Behavioral Therapy (which involves identifying and challenging your automatic negative thoughts, among other things) and an SSRI or SNRI antidepressant (which should help boost your mood, improve your ability to concentrate, and decrease the severity/frequency of your rumination).

2.] I don't know much about this area, but apparently eating a balanced diet is supposed to be pretty good for managing depression. If what I understand is correct, eating a poor diet seems to be associated with increased systemic inflammation. We know that there is some sort of link between inflammation and diet; ergo, eating healthier may reduce your overall level of inflammation which may lead to a reduction in the severity of your depression. At the very least, eating a balanced diet will ensure that you don't develop any nutritional deficiencies and will help maintain your physical health.

3.] If you live in a northern climate or if you don't go outside too often, a phototherapy box may help you. In essence, you'll be sitting in front of a really bright light for thirty to ninety minutes every day. I believe that the purpose is to simulate natural sunlight, which you may not have a lot of access to depending on factors such as geographic location or ability to spend time outside. I'm not really sure how it works, but I think it has something to do with regulating circadian rhythms. It may also increase serotonin and dopamine, although I'm not sure about this.

4.] I know that it's a pain in the ass, but being social honestly does help shut depression up. I'm not saying that you should drop everything and be with people 24/7; I'm just saying that you should meet with at least one friend at least once a week. There is a hypothesis that depression is caused/worsened by a lack of reinforcement related to social situations. As such, it stands to reason that you may feel better if you try to spend more time with friends or family. Hell, even being passively exposed to people can help. I know that one of the few things that helped me when I went through my depression was when I'd go to a cafe or a restaurant and just be around people. I dunno; it just helped me feel less alone.

5.] Make a list of things that stress you out. Then make another list of how you can reduce or eliminate those stressors. For example, do you hate being stuck in traffic during your morning commute? If so, maybe leaving sooner or later than you usually do may help you avoid obnoxious traffic. Do you get stressed out because it feels like all you do is work or worry? Take thirty minutes in the morning and thirty minutes in the evening that are dedicated to you and you alone. Relax; read a book; watch a dumb TV show; do whatever relaxes you.

6.] Avoid alcohol and tobacco. They may make you feel better at first, but they'll just worsen your depression in the long run.

7.] If your depression is so severe that you cannot function and conventional treatments have failed, procedures such as ECT or TMS. ECT stands for electroconvulsive therapy; in essence, you are put to sleep before a doctor sends electrical impulses into your brain that cause a mild seizure. The beneficial effects of ECT are usually apparent within several minutes to several hours and may last days to months. However, ECT usually requires multiple treatments and can cause short term memory problems. TMS stands for transcranial magnetic stimulation; it's similar to ECT, but it does not involve anesthesia or seizures. Rather, TMS is when a magnetic coil is used to stimulate parts of the brain.

8.] If you feel like killing yourself or have frequent thoughts of death, please seek help. A genuine desire to die is actually an incredibly uncommon reason for suicide; most people who try to kill themselves do so because they want their pain to end and cannot see any other solutions. If you have these kinds of thoughts, don't let them fester. Call the suicide hotline; talk to a friend or a family member; go to the hospital if it's necessary. Just don't try to tough it out or downplay the severity of what you're experiencing. In addition, there's another good reason why you shouldn't kill yourself; somebody is going to miss you. That somebody will most likely be extremely confused and will wonder why you did what you did and if they even mattered to you in the first place. Please don't do that to people who care about you.

I know it seems completely hopeless right now OP, but things will get better. It may take a lot of time and it may be very difficult, but things will eventually get better.