The best leaders know when it's time to leave. Others linger and hang on, well after their sell-by date.

How do you know if it's time to move on? Two factors often determine when it's time to leave - the political landscape shifts and the goals and desires of the leader change.

Rene had been hired to upgrade the department more than a decade ago as part of an overall initiative to retool the business as it adjusted to changes in the marketplace and to increased competition from smaller companies that were eroding their market share.

Her first task, to stop the bleeding, took nearly a year and included letting some staff go, adding new staff, and completely revamping the standard procedures for operating the department. It took a few years, but the department soon became one of the best run and most widely praised parts of the business.

For the past few years, Rene has been operating on cruise control, finding herself without any of the challenges that she had so looked forward to for most of her career. She's ready for the next challenge.

Gill was one of those whiz kids the company hired during its heyday when growth was in double digits annually and the future was rosy. Now, since the economy has slowed, internal opportunities have dried up and resources for new initiatives have been cut. The wind has been taken out of the sails of the business.

The rapid advancement that came with a skyrocketing company has stopped, and with it his interest in staying. Some of Gill's colleagues have moved on. Gill wonders if it's time for him to go, too.

Wendy has been a loyal and dedicated supervisor and mid-level manager for most of her twenty-plus years in the business, slowly working her way up to positions of increasing responsibility. Recently, however, she had not been considered for promotions into other areas of the business, despite her expressed interest in the jobs.

When she asked about the reasons for why she wasn't considered, she was told that despite her experience and performance, she was needed where she was. Wendy, feeling trapped and underappreciated, is wondering whether she will ever be promoted out of her current area at all, and if not, whether it's time to move on.

Len was hired by the previous CEO and had worked on several strategic projects for her during their seven years together. Then, the CEO left to take a similar job at a much larger organization.

For the past year, Len has repeatedly asked his new boss to meet in order to discuss how he can be of value. Meetings are scheduled, but are inevitably canceled at the last minute as "emergencies" have arisen that required the new CEO's immediate attention. He's not the only one in the same boat. Two other colleagues who worked directly for the former CEO have moved on - one followed her to her new company and the other found a position working for one of the division presidents. Len is working on his exit plan.

Javier was the HR department's Manager of Benefits and Administration before the merger was announced. The transition team is working through the details of the integration.

He realized that with many mergers and acquisitions, the support teams often face severe reductions as labor costs are trimmed and the administrative services are consolidated into one function. It's unclear how the two HR departments will sort themselves out, how many people will stay, and who the winners and losers will be. Javier is wondering whether he should stay to see how things will work out or whether to leave while he still has a job.

Leaders leave for a variety of reasons. Often, the timing is predictable and planned. At other times, it's less clear and less certain.

Being able to read the proverbial "tea leaves" and to anticipate what might lie ahead is the first step in deciding if it's your time to move on or not.

What is going on in your organization now? What does the future look like for you where you are? What else might you want to do? Are you ready for a change?

Ann Patchett provides advice in her book, State of Wonder, that applies to leaders. She wrote, "Never be so focused on what you're looking for that you overlook the thing you actually find."

Leaders are paid to make decisions and to solve problems. As they do, they may be unable to see what is really in front of them. By focusing on what they expect to see or what they have always seen before may prevent leaders from seeing what is actually before their eyes.

What steps can you take to be sure you see what is actually there and not what you expect to find?

My younger son, Josh, is a proud Penn State alumnus with season tickets to the Nittany Lions football games. In October, he invited me to attend a game with him in State College, PA.

After the game, we were discussing whether Joe Paterno would ever leave and we decided that unless something unexpected happened, he'd coach until he dropped. Little did we know that the unexpected did happen. Joe Paterno was fired. The game we attended was the last he ever coached and set the record for most wins in Division I football.

There's a lesson for leaders here. Leaders are responsible for every decision they make, every action they take, or fail to take, and every word they speak. It doesn't matter how famous you are or how much you've accomplished - your legacy is dependent upon everything you've ever done, with no exceptions and no excuses.