If we plan to offer life advice to him, I'll throw my hat in the ring because
I struggled with depression for about 5 years. A lot of this has probably already been said, but worth a shot:
1)
Stop the negative thoughts. Positive thoughts breed more positive thoughts, negative thoughts breed more negative thoughts. Your line of thinking will also affect your mood, so avoid negativity. And before you say "But I can't control what I think!" Yes, you can. It's all a matter of what you focus on.
2)
Set small goals. Rome wasn't built in a day. You can't change your life overnight, it's a gradual process. Instead, write small, achievable goals for yourself, like "I will attempt to strike up a conversation with someone new today." or "I will exercise at the gym every other day." It also helps to have some way to remind yourself of these goals (I use a phone app.)
3)
When talking with someone for the first time, don't sperg. There is a difference between passion and obsession. If the person isn't familiar with an interest of yours, broadly explain it. DO NOT DIVE INTO DETAILS, IT'S VERY OFFPUTTING. Let's take the hairdresser as an example. She asked you "What kind of games do you play on stream?". You do not dive into the intricacies of fucking Mario. Instead, say, "I mostly play games I grew up playing, especially mario games." If she asks follow-up questions or seems interested, then you dive into a LITTLE bit more detail. If not, then change the subject to something else. Which leads me to...
4)
Broaden your horizons. Having many different interests allows you to meet many different people. It also makes you look like a more interesting person, as you will have many more things you can talk about. Bonus points if it's a physical activity. Personally, I just discovered that I love skiing. If it's anything that makes you say, "That could be interesting.", try it.
5)
Do Physical Activities. It's no secret that Adam plays video games all day. Near unanimous research shows that lack of physical activity and sunlight dramatically lower your mood. Make one of your goals in 2) be exercise and fresh air, it will help a lot. It will also help you lose weight, it's not much of a secret that you're overweight Adam. Losing weight will definitely help your mood.
6)
Move into your own apartment. This may sound condescending, but having responsibilities and accomplishments are very rewarding. Living with your parents does not help your self-esteem.
7)
Consider religion. Life sucks, it's a fact. Sometimes you're dealt a shit hand at life, or you get beaten down by what life throws at you. There's a reason that religion has existed since humans first walked the earth, and it isn't just muh superstition. When life gets tough, trusting in a higher power can help you cope, and you aren't weaker or smaller-minded for it. I won't pretend to know Adam's views on religion (and I haven't read the entire thread), but if he is of the atheistic view, I have one thing to say: the nihilism that usually comes with such a view is a cancer on your emotions. If you don't think anything matters in the grand scheme of things, you have no reason to improve your life.