Thank you, Alfred, for your comments on the last two posts.  If I may further both discussions--

There are so many reasons why a change is due.  I'm a believer in the need for changes in leadership, even (or perhaps especially) when the going is good.  We need to let our leaders bow out gracefully and end on a high note.  We also need to be able to turn over as problem-free an environment as possible to our successors, so that they don't spend the first few months of their term putting out fires that you left behind.  The opportunity to lead allows people to come into their own.  It pushes back your horizons and forces you to mature. Other people need that experience of change if they are to progress in their careers. It would be selfish to deny them that opportunity.

And then, for my self personally, I really do need to move on to other things, to grow in other areas, particularly research.  The opportunities that have presented themselves of late are too good to pass up. I need to devote time to them. Someone else can mind the store.

I am grateful for the experience of leadership.  It taught me many things, one of them being the need to grow a thick hide.  You will have to take risks and you won't always be right.  Even the most "special" of us make mistakes or are turned down.  When that happens, you can't spend too much time nursing a bruised ego or a grudge.  You can't wallow or fret, at least not for long.  The experience should make you stronger.