Fell off the eating clean wagon....

I was doing so good and for the past 2months I fell off and I need some help on where to begin again.  I feel like I lost all knowledge and movitation on where to begin.  Can anyone help me?  I was running and I ran my 1st 5K and since then I really haven't ran.  I will walk on the t-mill but I can tell by my clothes I'm starting to gain.....I CAN'T get to where I was before I was pregnant. I feel like a failure....any tips!!  MUCH APPRECIATED!!