Answers to interview questions about an important goal you accomplished provide a keen insight into your character and motivations.
Another way of asking this question could be:
Even though the same techniques apply in structuring your answer, what makes this question different is sometimes it can take years to accomplish an important goal.
It's also a good idea to share one or two personal goals you've accomplished.
When you reveal one of your personal goals, people get a deeper insight into your character and values. They see you more as a real person vs just an employee.
However, if you do decide to share a worthy personal goal, it's best to share one that could also have applications in the workplace.
Good examples of personal goals you accomplished:
Any of the above personal goals would be great to share, but avoid sharing deep personal private victories that might be misinterpreted or unintentionally cast you in a negative light.
Good examples of work related goals you accomplished:
This situational interview question is very similar to the behavioral interview question, What was your greatest accomplishment?