I suffer from Social Anxiety and I have always been the "nice" guy who lets everyone walk all over him and push him around, but I will be honest, there have been a few things that have helped me significantly.
One of them may actually be surprising: it's models.
I have been privileged to make some amazing virtual friends with several cam models and have offline conversations many times with each - and yes a real virtual friendship, not only when/if I can tip them. Many times I have been unable to for long periods (I have not worked for 6 months right now for example due to recovering from an operation). But with these ladies, they made me realize I am not this kind of guy I thought that I was. I have lacked any kind of confidence ALL of my life and I have always thought I was 100% worthless and don't deserve anyone good etc. These wonderful ladies have gotten to know me and I with them and helped me to really understand that yes, I am not this handsome stud, I am not rich, I am not the life of a party and many other things BUT i am also not the OPPOSITE to those. With pretty much most things, I am AVERAGE. They have helped me to understand/realize and accept that this isn't a bad thing at all. So it has helped my confidence HUGELY (I have not become arrogant or anything, I am still not very confident, but let's say my confidence was 1/10, it's now 5 or 6/10).
The second thing that has helped me, and this is the most, is doing a course online for 11 weeks for helping understand and manage my social anxiety. It's a CBT (Cognitive Behaviour Therapy).
I am in the UK and it was free to do, as there are many schemes here that allow us to do things like this free because they understand how crippling it is to not be able to do regular and daily things everyone else can. I was EXTREMELY worried and nervous about doing this because I knew I would have to go outside of my comfort zones. It helps you to identify your triggers, what symptoms are, how to manage them and so much more. I did not have to go see a therapist or anything, so this made it easier - yet also harder cos I had to force myself to keep doing it.
At the end, you need to set yourself goals. 1 goal each day for 5 days. Each one must increase in how much it affects your anxiety. So Day 1 maybe go for a walk and your anxiety level is only at 10% but day 5 will be maybe going somewhere busy and doing something where you may need to talk to people and makes your anxiety very high, such as 80% or more. You need to stay and do each activity for 30 mins, because by then your anxiety SHOULD decrease by 50%. This, I was terrified of doing. The first 2 days or 3 days were fine and easy enough.
To put it in perspective, my entire life I could not even go and sit in a cafe by myself, and heck hated to do that with any friend/relative. I could not go on ANY public transport by myself. I would walk into stores and if I could not find stuff within the first minute or two, I would go home. And of course, talking to people... my god wow, just no thanks.
But now I have been abroad to Romania twice by MYSELF, that's going on multiple public modes of transport to get to the airport, navigating the airport, going on the plane and then navigating airport in a foreign country I had never been to and can not understand the language (trust me I tried i suck at languages lol). I can now go into cafes by myself and sit down and enjoy a drink at a leisurely pace. I can go into stores and not freak out because I can't immediately find something, and I will go look for it (and even ask if I can't find it still). I even went swimming by myself multiple times, went to the gym.. and lots more stuff which I NEVER would have been able to do had I not done this course. My problem was/is my brain: it created a wall inside and made ALL logic go right out of the "window" for me. I used to not realize I had anxiety problems because I used to think to have it, you must show physical problems such as crying, shaking, freezing on the spot, heart beating fast, sweating... and all that kind of thing you associate with it.
Of course, there is and always will be things that will still trigger my anxiety and make it really bad but with doing the CBT course, it helped me learn how to control and manage it. This will always be something in my life, but I have learned to deal with it and accept it into my life.
Apologies for the lengthy reply but I am hoping to let you know, I spent/wasted so much of my life (I am 32 now) with these issues and wish I had realised I had anxiety sooner and then do this course... The one advantage you do already have, is knowing you DO have anxiety problems. Now just try to force yourself into doing something like I did: Cognitive Behaviour Therapy. It really can work. Worth looking into and trying, if you can.
Merry Christmas and have a great day