Here’s what I thought about my career in my 20s: work hard, over-achieve on deliverables, be the one who can be trusted with the tough assignments. Then, get the raise, get promoted, become CEO. And, yep, most of the time, working hard does yield results. But then there was that time I was running Merrill Lynch and was "reorganized" out of a job — even though the business was growing, ahead of plan, and gaining share. Oof.That’s when I learned the hard lesson that (as Carla Harris , a senior banker at Morgan Stanley, articulates): All the important decisions about your career are made when you’re not in the room. People decide to hire you, fire you, promote you, fund you, send you on the overseas assignment, all when you’re not there. As I called around to the members of the company’s board of directors the day after I lost my job, what I heard was that no one in the room was fighting for me.Let me add one other lesson to Carla’s: It doesn’t cut it to rely on human resources (or Talent Capital Management or whatever your company calls it). There are no HR fairy godmothers. The idea from your parents’ time that HR will steer your career — and serve as the person who fights for you — went out the window with MySpace. So how do you ensure that you have someone in the room fighting for you?Well, you still need to work hard, and you still need to over-deliver, but I would strongly argue that you also need to have in place your Personal Board of Directors. Those are your mentors, your sponsors, your confidantes, the people you can turn to when you’re thinking about a career transition — for the kind of advice your boyfriend, your parents, and your best friend from college just can’t give you.Ahead, some advice on how to set up a Personal Board of Directors. These people won’t guarantee that you’ll be protected from sudden career shifts, but they will be there to help you if (or, in many cases, when) the rug is pulled out from underneath you.