As a personal trainer my job isn't to "torture" you. It is to provide you with guidance and knowledge to enable you to be active and in turn feel great.
As a client, your job is not just to do everything I tell you blindly. If you have questions, ask. If you are hesitant, speak up. If there is something in particular that you would like to do - tell me.
This past Tuesday, B just wanted to destress. Instead of an hour of cardio, weighted exercises and body weight exercises we did yoga followed by some treadmill intervals. Why? Because that's what she wanted to do. Rather than forcing herself through a workout she really didn't want and would likely resent herself and me for, she expressed her desire and was rewarded with some much needed relaxation. Why did we do intervals? Because she wanted to run. Simple as that! Showing up really is the majority of the equation.
Moral of the story as a client: speak up. Listen to your body. Trust yourself. Trust your trainer.
Moral of the story as a trainer: Trust your client. Respect your client. Respect your own time. And most importantly - understand that at the end of the day your client has hired you to provide them a service and even if that service isn't what you had originally planned to give them, be prepared to switch things up for their benefit.