You've got the interview!" may not be quite as thrilling a message as "You've got the job!", but it's music to a candidate who has spent many grueling hours (days?) creating the perfect résumé.
Difficult as the résumé writing may have been, however, once an interview is scheduled, a candidate's real work begins. Now it's time to get in shape mentally and physically for an event that could have momentous impact on one's career and life.
If you're on deck to have an interview soon, or if you expect that an opportunity will arise in the future, don't delay toning, not only your job-specific knowledge and skill set, but also your corporate awareness, your interview style, and even your physical condition and appearance.