What you do matters. Being needed matters, yes, but being needed may not be synonymous with work that makes you feel vital, makes your contribution feel important. Are you needed because your mind, your skills, your craft is unique? Or are you simply filling a gap that neither supports nor nourishes you?
We love to feel challenged, and we love to overcome those challenges using only the gifts we have at hand--that kind of work is vitality, no matter what occupation you happen to practice. The salary involved doesn't matter because, as nice as money is, it does not measure your worth. What measures your worth is that moment just before sleep when you can honestly marvel that, yes, you did good work today.