So, I have already accepted some interviews for graduate schools. I tend to get really nervous (going to take medicine before I go)...but I need to know answers to certain questions and I can't think of a good answer:

Like,

"What was the biggest obstacle in your life?"

"If you had to do one thing over/regret one thing, what would it be and what would you do to correct it?

"How you have dealt with an error you made and fixed it?"

If someone can answer or help me figure out an answer so that I feel like I won't die during the interview, I'd really appreciate it.