Experienced this before. You can try to find out your facts to the situation, and find out their facts that make them think the way they did. that's what someone told me. present what you know or feel calmly, and politely to that person, and explain clearly why you feel differently(you can do it with the help of the facts that you gathered). Tell them in a firm manner that you will think over their advice, consider the pros and cons, make a decision, and not let them force their ideas on you.