Getting bigger might help but alone it probably won't fix it. Lots of big insecure guys in gyms.

Getting out and about, getting involved in stuff with others, playing a sport where you fail, pick yourself up and try again while your mates encourage you will help.

I would not think at all about cosmetic benefits of lifting. Get strong in a useful way. Having a big neck should be very low on the usefulness list. A high calorie diet is only useful if you are burning a lot of calories, otherwise you will just be a fat underconfident guy before you know it. Make sure you do solid compound lifts, with 4 sets of fairly low reps. Get strong, then you will feel the results, you will measure your success as that bar gets heavier and that will make you confident that you can get stuff you want to do done. Some aerobic fitness can also do wonders for confidence, just gets the hormones regulating better. Seeing results from say running or swimming will also help gain confidence.

Apply yourself at becoming better not at appearing better and confidence will come.

Read No More Mr Nice Guy and When I Say No I Feel Guilty. Google a pic of the bill of assertive rights, maybe print it as a reminder if needed.

Implement that shit.

I think that becoming more assertive for me is much more important than the getting bigger part.

100% right, but do both

Two mandatory reads: 1) No More Mr. Nice Guy, 2) When I Say No I Feel Guilty.

Also, 0) The fucking sidebar.

Also it's important to stop thinking that you are the focus of the universe.

be respectful, considerate, nice, caring and put everyone first ahead myself

this is all correct and proper upbringing, but only when in the context of your loved ones and people that reciprocate with the same behavior. you're fucking up when you're like that with strangers (especially kafirs) - that's not part of the culture, that's not a failure in the values instilled by your upbringing, that's a you problem (i'm assuming you're muslim).

It's also important to stop over analysing every single interaction. You were in an elevator with not much room, some other guy tried to get on, no big deal.

I swear things have got worse because of the lockdowns - everybody's underlying mental health issues just got worse x100. So it might be that you are mildly socially anxious, somewhat spergy... no big deal. Sometimes there isn't some big underlying problem - you just need to get out and experience life, make some mistakes, re-calibrate and keep moving keep learning.

Sounds like you are going through paralysis through analysis. You end up seeing every little thing as a problem. There is another guy on this platform (more than one) that keeps saying that people are 'disrespecting' him, which to me sounds like mental illness. More likely is that nobody notices him.

Felt bad and deleted my comments, but seriously how old are you?

when there’s no space and I was already standing in the corner.

Don't stand in the corner. This is inviting people to talk the rest of the space. People literally cannot judge volumes and regularly fuck up estimates of "will I fit".

I said yes

Yep, pushover.

Correct answer is "there's no room".

I’ve always had this expectation that people are courteous,

they are mostly not

because I was raised to be courteous myself.

This is the horrid thing that nice parents do to their children: they pretend the rest of the world is nice. Mostly they are not. Get used to it.

I was also raised to be respectful, considerate, nice, caring and put everyone first ahead myself (The perfect recipe for disaster as a man.)

Correct

I am skinny as hell at 180cm. I have been eating at a caloric surplus for the past few weeks. I’ve gained some weight, but I still need to gain at least 10 kg to physically exist. I intend on working on strengthening my neck, to make it thicker.

Good

I have noted advice given on another post that I should work out and get bigger, but also become more assertive.

Correct

I think that becoming more assertive for me is much more important than the getting bigger part.

Do both

How do I become more assertive while I get bigger?

Look, this is a journey. You have to walk it to get there, you can't jump to the end.

You incrementally learn to put yourself first. You can't win em all...... this guy in the elevator..... you should have:

• Taken up more space. This earns you respect.
• Don't fall into his frame of "yes the elevator is going down,, hop in"..... instead answer a different question.... "there's no room".

This exact situation won't happen again, but similar will. Get used to it. Practice doing better.

Think before responding. Don't answer questions straight away. No auto responses. Don't automatically be nice. You want respect, you don't need to be liked.