Whenever possible, you should speak about your achievements from the perspective of an employer (helping them to find new customers, helping them to improve their reputation, building good atmosphere on the workplace, earning more money, etc), rather than achievements from your own perspective (getting promoted, earning a degree or certification, etc).
Nothing says “hire me” better than a track record of achieving amazing results in past jobs, so don't be shy when answering this interview question! A great way to do so is by using the S-T-A-R method: Set up the situation and the task that you were required to complete to provide the interviewer with background context (e.g., “In my last job as a junior analyst, it was my role to manage the invoicing process”), but spend the bulk of your time describing what you actually did (the action) and what you achieved (the result). For example, “In one month, I streamlined the process, which saved my group 10 person-hours each month and reduced errors on invoices by 25%.”
Example: “As an experienced, service-oriented professional with more than a decade of experience working in boutique salons, I thrive on creating a welcoming environment for all clients and providing the highest quality skincare services. My specialized training and strong interpersonal skills have helped me become adept at developing long-term, trusted relationships that help to build a loyal client base. Some of my clients have been with me since the beginning—more than ten years now. These relationships are the reason I’m excited to go to work every day.”
Example: “Earlier in my career I noticed that because I was so enthusiastic about my work, I had a tendency to say ‘yes’ when I should have been saying ‘no.’ At one point I ended up so overwhelmed by my workload, taking on so many projects, that I was working evenings and weekends. It was stressful, and that stress affected my production quality. I realized this was counterproductive, so I started using workload management tools to set better expectations for myself and my teammates.”
"Choose an answer that shows that you can meet a stressful situation head-on in a productive, positive manner and let nothing stop you from accomplishing your goals," says McKee. A great approach is to talk through your go-to stress-reduction tactics (making the world's greatest to-do list, stopping to take 10 deep breaths), and then share an example of a stressful situation you navigated with ease.