I was finally diagnosed with heart failure, and quickly after that, hypothyroidism, around 2009.. I was 29 and I'd been very ill for over a year..
In a way it was a relief but I was petrified I would drop dead at any second (technically, I still could, but there really IS only so long you can maintain that level of terror for!).
In 2010/11 it was determined that, due to historic symptoms and other previously unnoticed symptoms (or the ones noticed but put down to me being fat/idle/a whinger) I in fact have Ehlers Danlos which is why I went into heart failure at 29 (valves stretched) ..
By that point actually although life changing this was a massive improvement as it made things clearer, I knew roughly what to expect, it was clear what could and could not be done.
I have a prospective lifespan of under 10 years which at 36.. sucks, theres no way round that one.
Theres always the chance the Drs are wrong and I'll live longer than that, but what quality of life I'll have, I don't know (if its the gasping and wheezing and fighting for every breath I had during active heart failure then I shall be checking out early. For sure.).
Knowing that I really AM ill and that actually the reason I didnt like doing stuff and found stuff hard was because in fact it WAS far harder, and far more painful than it was for anyone else.. was a revelation and a relief.
Being told NOT to do stuff (v little exercise, no bending, no lifting, basically sit on my ass and do nothing) sucks - I push the rules a bit, I have a manual wheelchair not an electric as this means I can exercise without hte risk of falling but I am still not supposed to get out of breath.
Getting my head round preserving what mobility I have now for the things i REALLY want to do - thats pretty hard, not a lot of people immediately grasp that I use a wheelchair to save and slow down the damage I am doing to both my back (I have the arthritic changes you'd see in a90 year old in my spine!) and my heart... but this means i CAN stand and walk short distances (in a lot of pain but im practiced at ignoring that) - so I still go without the chair for work (I go to peoples homes and not many peoples homes are wheelchair friendly).
But I have along the way learned to really not give a fuck what other people think, between me and my various consultants I have found a way forward that lets me do much of hwat I want whilst limiting the damage a sensible amount.
I try not to think about the fact I won't get 'old' old.. and that I do need to get on with stuff because there won't be a 'tomorrow' at some point, but I daresay this is something everyones gotta deal with eventually (my dad is 'old' old but doesnt feel like he is and is raging against it!).
Honestly, whatever it is... we are all far far stronger than we think - you'll get on with it, you'll make the best of it - you might be angry or pissed off or sad but you'll find a way to deal with that.
One thing I will say - do NOT compare yourself to others - the shit you have to deal with is yours and it is important and it is serious to you - it doesn't matter a tiny bit if it looks on paper like its less serious than my shit, or someone elses shit!
This whole '#ah but someone else has it harder than you, cheer up' bullshit really does need to stop. YOu aren't dealing with someone elses life, you are dealing with yours!