It's a Sad, Sad Sunday

I'm missing my youngest son tonight.  Sunday evenings are hard for me.  What should I be doing with my time, and what do I actually do?  Son #3 could be depended on to liven things up with his smile, his humor, his music, or by creating some action by bringing friends over.  I guess I don't create enough action of my own.  Or maybe this is just the let-down after the busybusybusy summer I've had.  Good thing I've got work starting this Thursday.  I need more structure.