Empty nest again...

Somedays I feel restless and today is one of those days...
How do mothers survive who have spent a good part of their life with their kids. Now its empty nest syndrome again.. .. its been for a while and I had pretty much settled myself to "keeping myself involved" in various social activities, volunteering and surfing the net. Come summer- kids came home for a week or fortnight and then left for their summer internship and class. I feel their absence all over again...
I know I can handle it , I am mature.