If you closed up shop, would your customers miss you?
If you stopped being an elementary school teacher and became an administrator, would your students miss you?
If you left your sweet sales job, would your clients miss you?
If you stopped writing your daily blog, would your readers miss you?
If your TV show switched time slots, would your viewers miss you?
If a role-player on your team left, would she miss you?
Ask this of yourself. Will you be missed?
The answer maybe no despite your current success (material or otherwise).
But longevity and truly valuable impact require the answer to be yes. Will you be missed?