I freeze in interviews, tips? after 10 years as a procurement assistant

I have an interview on Wednesday and my stomach is in knots. I have read a lot of threads here and could not find my exact situation. I have practised answers but they sound stiff. What calms you down?

Thanks for writing this out. I went through something close to it 14 months ago, and it settled down once I kept a simple log of every call and form.