Physical Therapist/Personal Trainer here. I'll share my philosophy because I get people like this regularly. Remember at the end of the day, they came to seek YOU for guidance, not the other way around. You need to educate them and put your foot down, you may be surprised how they change their mind. If you just cave in from the start, they will start trying to run the show. If they still do not want to listen then, do what
>>76354060 said. Have them to baby exercises and just collect their money. If they are unhappy with their progress, then give them the reality check otherwise keep taking their money. Best thing anyone ever told me was to not care more than the client. If they do not want to trust your knowledge, then you should not care to go the extra mile for them.
If you do want to try changing their perspective, don't be confrontational, be inquisitive:
>Why don't you want to do X?>What don't you like about X?Once you know their answer, then you have something to address. Don't go on an autistic rant about why its good for them without addressing their concerns.
Welcome to working with people. Some days its like running a daycare for grown ass adults, but when you do get good clients it feels rewarding.