I lost my mojo

I'm really struggling with running motivation as of late.  When I first started running, I had something to prove.  I wanted to prove to myself that I could run, and I did.  Then I decided to train for a half marathon and every training run was exciting and new because it was something I had never done before; a new challenge.  It was pure passion and dedication.  Then I completed a half marathon, proving to myself that I could (and it felt amazing).  Now that I'm running with no end goal and no race on my schedule it's just not the same.  The excitement has faded.  I ran a four mile loop last night and struggled the entire time.  I'm sure I walked more than I ran.  I hated almost every single minute of it, but did it any way because I know it's good for me and I'm terrified of gaining back the twenty pounds I lost.  Most days I think "if I have to run through Barber Park (my regular running route) one more time I'm going to go crazy".  Where did the love go?  Do you guys ever feel this way?  I need a new route.  I need a new goal.  I need help!