"To not get" meaning "I don't understand" which is fast becoming a euphemism on mn and elsewhere for "I disapprove of how you live your life and I am expressing it through a weird arrogant faux naïveté"
Does it REALLY not occur to you that :
It may be very painful for them to do even minimal low impact exercise
They may be embarrassed of how they look/appear to others at the gym or otherwise publicly exercising
It may be something they've been advised to only do under strict supervision if at all which you may not be privy to and aren't entitled to know
That it's ultimately their choice?!
You sound very much as though you think you know best when you can't possibly know nor are you entitled to know the ins and outs of their medical and/or personal history, eg I have a relative who developed exercise addiction (yes it's a real and very damaging condition associated often with eating disorders and that sort of mental health issue) and as such can only exercise in certain ways and at certain times in order to control the addiction.
I am disabled following a car accident some years ago and now have a degenerative spinal condition. I'm also overweight. The number of people (inc hcps) who've given me utterly clueless and potentially dangerous exercise advice is shocking tbh.
It would not simply "be uncomfortable" for me it could land me in a wheelchair!
Do you honestly do EVERYTHING according to it being the healthiest option? Eat a completely unprocessed plant based diet? Live in the country away from pollution? Minimal use of screens? Don't drive? Of course you don't! You will do things which aren't optimal for health too - because that is your choice and your decision - respect the choices of others too.
Your DH’s PT must have been pretty shit what a supremely arrogant comment! You have no idea of the full facts of the situation. Even two people with the same condition can require very different treatment based on any number of factors.
So I kind of think I am entitled to preach seeing as I’ve been there myself no you're not - because YOUR story and medical history is NOT anyone else's that's just not possible.
It worked for you - great - but please for the love of god don't pester others and make people who probably already feel pretty shit about their lives feel even worse just because they don't follow your (potentially dangerous) advice. I hope to god you aren't "advising" people with medical issues as you clearly aren't qualified and also lack a great amount of understanding how to genuinely motivate people
It's like fat shaming - it doesn't work and if anything it's more likely to make the person think it's pointless even trying to change things.