I know the Covey precept of "Sharpening the saw" is cliche by now - but sometimes cliches are cliches for a reason. If you don't stop and maintain your tools on a regular basis, your tools become less effective. As a writer, your tool is YOU.
For my part, I've been so busy I haven't taken the time to step back and really plan, so that I can be more focused. That's why I'm heading out of town for a personal retreat tomorrow, to focus and really put some goals and plans down on paper. I know me, and it will be so very tempting to actually get started on some of those goals, but if I don't make sure I segregate this time specifically for the planning, it's a lot harder to make it happen later.
All that said, I think what it really comes down to is Balance. You can't focus solely on yourself, and you can't put yourself last. You have to find the right balance that will allow you to accomplish your own personal goals and meet your own needs while also balancing your other priorities like your relationships, career, etc.