What would it be like to quit your job and start over in a more appealing career? If you are an older worker, you may think that a major career change would require overcoming too many obstacles to be worthwhile -- like age discrimination, new technology or a salary cut. But according to Helen Harkness, author of Don't Stop the Career Clock, the real obstacles to a midlife career change may reside in your own mind. Harkness argues that several myths surrounding midlife career changes keep people from pursuing their dream job. Which myths do you subscribe to