Song inspiration can come from anywhere.

I can have a great day and write a song about it.  I can also have a terrible day and write a song about it.  The bottom line everything is an inspiration.  Good stuff is great but you need the bad stuff too.  One of my most popular songs was inspired by a car accident that happened to a teenager from the neighborhood I used to live in.  It was horrible.  It really impacted me and I didn't even know him. It got me to thinking about what I would say to my Boo if I suddenly died.  Depressing and sad but as everybody knows, not everything in life is sunshine.  My point is, notice everything around you.  Take it all in and channel it into your writing.  My song, When I'm Gone, touches on some deep emotions and it never would have been wrtten if I only used the good stuff.