Book excerpt: Your next act starts now. You're ready for something new, but it's hard to start over. Just the idea of trading the security you have now for the unknown or throwing away the education and time you've invested in your current career can plunge you into a swirl of indecision and anxiety. But mixing things up every few years is an increasingly normal and cyclical part of a healthy work life--a way to gain new skills and stretch your existing ones by applying them to different contexts. Whether you know what you want to do next or you're still evaluating options, the HBR Guide to Changing Your Career will help you: Imagine other professional selves Identify the skills you need--and those you already possess that will transfer to another industry Assess the financial implications of the change you're considering Try out new roles without endangering your current job Explain a seemingly winding career path Pitch yourself into a new role