The Upside Down of Goal-achieving

I remember at various times in my life when I would feel a let-down after a big event or achieving a big goal.  After college, I was too busy moving to Boston and finding a job to support myself to feel down:  I was starting a new chapter of my life and too young and loaded for adventure to care about downsides.  But after promotions or getting married or becoming a parent, my emotions not so much crashed as they took a serious dip.  Then the reality of maintaining that higher level of doing and being snapped me to in a hurry - especially with a little baby.

So I finally self-published a book, which I now realize became a much bigger part of me than I thought.  It took me over 8 years from start to finish and now I sense that writing it was only the beginning of the process:  suffice to say I should've been a marketing major.  I'm so proud of myself for finally completing it but the quasi-funk of getting myself psyched to set another goal (besides the ever present one to lose weight!) has lasted a little longer than I anticipated.

Does anyone out there have a similar story?  Maybe after running your first 5K or reaching your weight loss goal?  I'd appreciate your weighing in.