Preface: This will read as though I'm making a lot of assumptions about parent's beliefs/views. I am not. They may or may not share the views I argue against here. This is intended for a general audience where I do routinely here these views articulated.

I'm not GP but did the same thing (ignoring my therapist's specific plan) because:

1. Every time I see him it costs me hundreds of dollars, and if we made any changes to the routine he will want at least 6 more visits.

2. When I asked about increasing the weight over time, he told not without first coming to another appointment because it would be unsafe. He also would only allow small increases at a time. Surely only for safety purposes, definitely certainly not in any way influenced or incentivized by revenue...

3. I'm not an idiot, and this is not rocket science. I know my body pretty well on account of living in it and with it and having been engaged in intense physical activity off and on my entire life.

4. Some of the exercises he gave me were wrong for me anyway. I have torticollis (something that he missed entirely despite me telling him about it at the time, though I didn't yet know the technical term for it) which necessitates some changes to the routine.

I think it's important as patients not to listen to the people who say, "You're not an expert. Shut up and listen to the experts." or "Are you a doctor? Then stop using your brain immediately and cease all functions of rationality and accept what you're being told." I've known plenty of experts (including myself in my own field) and being an expert and/or credentialed doesn't magically make you omniscient. Some of the most interesting and fierce debates happen between two people who are equally credentialed, and both of them can't be right.

It's your body and your life. You have insights into it that nobody else does. Be humble, know what you know and try to know what you don't know. Treat your doctor like an incredibly wise and experienced friend and give their opinion heavy weight - they are most likely correct. But that doesn't mean they are infallible. Sometimes they don't have enough information on your issue, sometimes it's just not something they have a lot of experience with, and sometimes they are just plain wrong. It turns out that a human with a credential is still a human. Forgetting that and treating them as god-like all-knowing machines won't make them such. You still have to engage your own mind, and sometimes that will lead you to finding a new doctor or in some cases just dealing with stuff yourself[1].

[1] I would hope it goes without saying, but in this current environment I think it bears explicit stating: Just because doctors are fallible and sometimes wrong does not mean whatever quack on the internet is right. There is some great information on the internet and some real quality people producing content. There is also a mountain of bad content that at best will waste your time and money and at worst could hurt you. I am in no way advocating that you shouldn't see a doctor or trained professional. You should do that. Just don't turn off your own ability to think when doing so. I do advocate "do your own research" (a phrase that has unfortunatley come to mean more than its face value, which is unfortunate) but step one or two of that research should (in most cases) be to ask a doctor!