Interviewing isn't easy. The employer is the customer and you're the business-of-one trying to prove you're the best service provider for their job. Studies show it costs a company as much as 130-140 percent of your salary to hire you. That includes things like benefits, taxes, training, etc. The stress of choosing the right candidate worries hiring managers. The result is a series of intense interview questions designed to let them "kick the tires and look under hood" before they invest.

Behavioral questions = Let them inside your head.

Hiring managers often use behavioral questions in an interview in an attempt to have you reveal your true professional self. These are open-ended questions designed to make you give longer answers. Your answers will demonstrate your personality, aptitude, and experience level. These three things matter greatly to employers who choose a candidate based on his or her ability to fit in with the company's culture. Here are seven intense interview questions you should always be ready to answer.

1. What's wrong with your past/current employer? This question seeks to understand what's driving you to leave your previous job. Happy employees don't go on interviews for new jobs. The hiring manager is trying to see if you have unrealistic expectations of employers.

2. Tell me about the worst manager you ever had? Again, seeking to understand your expectations, the hiring manager wants to know what kind of management style you don't work well with--especially if it's a style the hiring company currently uses.

3. What's the worst job you ever had? A hiring manager needs to know what type of work disengages you. He or she also wants to understand what (if any) attempts you made to fix the problem. When unhappy, are you proactive and try to fix your situation, or do you sit around and get disgruntled?

4. Why are you better than anyone else for this job? A test to see if you can balance confidence with humility, this question is designed to see if you have a grasp on reality and can articulate how you are different from the competition without resorting to "throw them under the bus" tactics.

5. Why were you fired? For those that have been involuntarily terminated, you need to be able to objectively share what happened and be accountable for your actions. If you resort to blaming and explaining your way out of any wrongdoing, you'll be dismissed as in denial.

6. What are your weaknesses? Nobody's perfect. If you can't discuss your areas in need of improvement, then you aren't self-aware enough to grow on the job. In fact, if you can't explain how you are already trying to minimize these weaknesses, then you are showing a lack of understanding about the need to always be improving as a professional.

7. Tell me about a time when you had to work with a difficult person? This question gets to the core of what you're like to work with. The hiring manager needs to know what type of co-worker you struggle to collaborate with and whether you know how to find a way to work together successfully with that type. You will be paid to do a job, and that means getting along with all types of people, even ones who don't work like you do.

Tip: Hiring managers hear what they see.

One of the biggest reasons a hiring manager asks intense interview questions is not to evaluate your answers, but to evaluate your non-verbal communication skills, i.e., your body language, facial expressions, hand gestures, eye contact, etc. Hiring managers can tell when someone is acting nervous or untruthful. That's why everyone should work on their interview answers as much as they can before they go to the interview. It will help you relax and communicate with more confidence.

A final thought.

The questions above are designed to help the hiring manager understand how you have interpreted past professional experiences and whether or not you've used what you've learned to become a stronger professional. What you say and how you say it tells a hiring manager a lot about your anxieties and frustrations as they relate to work. If you aren't careful, you will provide an answer that can get you disqualified. The best way to avoid making a mistake is to invest time in preparing for interviews. Employers don't want to hire high-maintenance employees. Show any sign that you might be difficult to work with and they'll pass on hiring you.