This is a good thing to wrap your head around; it will give you much serenity. Its a hard sell to most people though. We believe in our powers of persuasion (or coercion) and are often confident that we can change someone's mind. Now, someone may change their mind, but that choice is theirs, not ours. If we share our input with them and they don't change their minds, then it descends into nagging. Ewww.
I love Dave Ramsey. He's a radio guy who talks about money. He's really helpful and smart and entertaining, but that's not why I mention him. He often says "he persuaded against his will is of the same opinion still." I'm pretty sure he didn't make it up, but I think it's a great saying. And it's true.
A lot of time is wasted in and out of sessions trying to "change someone's mind" about something. I see people try a myriad of different approaches, descend into nagging (or worse yet, bullying) and get absolutely nowhere. IT DOESN'T WORK. I sometimes think that we think if we just keep talking we are going to say The Thing that makes someone change their mind. Actually, the opposite is true; people become more inclined to dig in their heels and tune it out.
The thing is... everyone is their own process (including us). WE usually know the facts and don't need people to beat them into our heads, i.e., "Smoking is bad for you!" "Greasy food will hurt your health!" "You spend too much money!" or ....fill in your own. WE change our minds, and hence our behavior, because we get THERE in our process. Think about it; did anyone ever quit smoking because before someone told them they didn't know it was bad for them?!
So someone is not doing what we want them to do, or they are doing what we don't want them to do. We may have five thousand arguments in our heads but the best thing to do is to practice ACCEPTANCE. Accepting something doesn't mean we like it, it just means that it is what it is and we can't change it. (We really can't). LET GO. You are beating your head against a wall!
