"and here lies the biggest challenge I have on my TMS journey ie how to live one’s life in the catastrophe of the symptoms."
My suggestion is to first recognize the desperation - notice it, and don't do anything at all with it.
Ways to train yourself: you don't need to use one method, you can experiment and try multiple ways. I don't find one method works for myself. I've got a lot of old habits and false beliefs to work through and I like to approach things from various angles.
1. Claire Weekes float method
2. notice the desperation and catastrophic thinking and just let it be
3. follow the catastrophic thinking - just let all those thoughts blossom in your mind and notice where you have truth and where you have false beliefs. Thoughts are not your truths. They are just thoughts - crap the mind generates because that's it's job. Slowly you'll begin to see what is absurd and what you hold dear. Perhaps the things you hold dear are also not your real truth...which is what things like journaling can help you to bring to the forward.
4. Use purposeful distraction: not to avoid emotions but to keep your mind from going down the same path. Living in fear and being scared isn't an emotion - it's a state of mind, so you can turn your mind from that stuff by investing your interests elsewhere.
5. Notice your personality traits and begin deciding what does and does not serve you. Does being perfect about turning your mind from every single negative thought serve you? Big Key - you don't need to turn your mind from every single negative thought! You simply need some balance - which right now means you tip the scale towards less negativity to train your mind but it doesn't mean you get rid of every single difficult thought. You change your reaction to these thoughts, but you don't have to erase them. Our first though is often a reaction. It's split second "OH NO" - but what you do next is what you have control over. Instead of "OH MY G*D, this is HORRIBLE and now I've made it worse by FOCUSING on it" you might be "OMG" and then "well, there's a reaction!, let's see where this goes right now in this moment if I take a few deep breaths and move on with my day".
Give yourself some grace, search for some peace in your mind. Simply STOP searching and researching this medical stuff. If your mind is busy and feels the need to research and search, do it with something that is a hobby or interesting outside of this physical fixation. to focus on things other than TMS).
Monte used to be a member of the TMS Wiki and had a great blog. He termed his method of TMS work as Thinking Clean. His approach to mindset was to note that mindset has a huge influence on the nervous system, and your "psychic" or "spiritual" energy.
Here's Monte taking about his method (as I said, his website is now down, but you can get the gyst from this video)
https://www.tmswiki.org/forum/threads/tms-think-clean-the-transforming-theory-for-tms.4668/
I can't find all his posts right now, but I can find a link to one of his videos explaining his method (his website is no longer functional, and he's moved on in life
@Sita has made wonderful posts about how she lives her life and it's very much in accordance to Monte's methods of "Thinking clean".
No Dr. Google at all. No following your mind down the rabbit hole of your obsessions. If you are a person who obsesses, do it about some sort of actual interesting hobby or professional endeavor ... something that benefits you as a person instead of feeds the TMS beast.
For at least a time, avoid a lot of news, gaming, music, movies, fiction and non-fiction which are full of violence and negative rhetoric. You want to tip your scale towards less negativity to feed off of. This does not mean avoiding your feelings and emotions - and you will certainly be able to add back some of these things in your life...but now is the time to notice how they are effecting you.
There is loads more, these are just a few main points he would make and they have all helped change my mindset over time.