I freeze in interviews, tips? after 3 years as a delivery driver

I get tongue-tied when I am asked about my weaknesses. Thank you in advance. I want to come across as confident and honest. How do you prepare answers?

Prepare three stories with a clear beginning, action and result, and adapt them to the questions.

Thanks for writing this out. I went through something close to it 12 months ago, and it got easier once I kept a simple log of every call and form.