Here's a bit of knowledge from Captain Obvious - job interviews are a stressful experience! It's true, there's simply no way around it. The interview process is an evaluation of you, your experience, and your future potential. While in reality the interview is just a conversation between a few individuals, it's clearly a very important conversation which impacts your future. You need to convey so many qualities and strengths about yourself, in a short time, and simultaneously at that. The interviewer sits there and interprets all that you are conveying, both intended and unintended, and you know it. So, it's understandable that you could feel stress.
But, let's consider the possibility that stress as a good thing for a moment. The potential stress of the interview should cause you to over-prepare, even before you arrive. That means that you'll be able to tell your story with excellence. Bonus! The potential stress will ensure that you take the process seriously, which means you have the opportunity to demonstrate what a responsible employee you will be - that's another benefit built right into the interview process. Finally, you cannot lose sight of the fact that stressful situations are required for personal growth. If you have a strong desire to grow as a person, you must stretch yourself where you're uncomfortable. If you don't learn something about yourself through an interview process, it's a missed opportunity for self-development.
So, how does one manage the stress of an interview and remain focused? Here are a few tips to consider:
1) Embrace the stress: Since you know the experience will be stressful, use the stress to your advantage as talked above. I hear colleagues and interviewees complain that they wish the interview process would be more "real" and not so "fake." When I deconstruct what they mean it comes down to not being prepared, the stress of the process and the uncertainty of the outcome. Given this is a dynamic of the interview process that you're unlikely to change, go with what you can control and Prepare, Prepare, Prepare! You'll be amazed how that can help.
2) Think through not only WHAT you will say, but also HOW you will say it: Many people only focus on the WHAT portion for interview prep. They think through their answers to common questions, and might use an interview framework to ensure their answers are clear and concise - such as the Context, Action, Result (CAR) format. While this is great, it's insufficient prep. You must also consider the HOW in the delivery of your answers. Interviewers are evaluating your communication style in many ways. You can deliver the same exact words to answer a question in two manners and get very different results. Stories told with passion and excitement change how they view you for the better. Conversely, a story told in a boring manner will work against you - guaranteed. Non-verbal communication is critical to manage.
3) Be conscious during the interview: Interview stress often leads to stomach butterflies right before the interview begins. This is great, because it ensures you are on your toes. However, many candidates quickly lose that edge 2-5 minutes after the interview starts, and we have 45 minutes to go. Ensure that you are constantly aware of you and your surroundings while interviewing. Watch the interviewer for non-verbal clues, and be responsive to those as needed. Ensure that you are "re-centering" yourself after you answer each question. Take the time in the small breaks to ask yourself - am I representing my brand the way I intended? am I talking with passion? am I displaying great energy and enthusiasm? If you make a habit of this after you finish each question, you'll be in great shape to make a solid impression during the interview.
Interviews are tough, there's no doubt. That said, the more you can reframe the stress as s good thing, the better you'll feel about the process and the more likely you are to have a successful outcome. Stay centered and do well.