To go along with that line of reasoning, of standing up for your beliefs that is....

Get the point across that what works for one person (your mom for example) may not work for you at all. It is very tough to argue with the law of individual differences.

It is not necessary for you to ascribe to her belief system or for you to rationalize things as she does. Listening to her, respecting her advise and goodwishes is fantastic.

But that doesn't mean that you should take action based on her every piece of advice. Your relationship could improve markedly once she realized you plan to live your own life and reason everything you do out for yourself. Just don't approach it sounding hostile or disrespectful. She doesn't get very far with you when she does that, no?