Been there, done that - I completely understand where you're coming from. For me, it's always been very hard to follow a plan. I finally got tired of beating myself up for not being able to stay with it, so I just accepted the fact that I'm not going to be perfect. I have my moments of weakness, but then get back on track at the next opportunity. That may not be the best of advice, but the key is NOT TO GIVE UP!
Everyone has their triggers for overeating, but at the same time everyone has reasons to stay motivated. I'm trying to write some of my motivations down, no matter how goofy they sound. Like being able to walk down the hallway without hearing the swish of my thighs rubbing together.
Or being able to fit my backside into one of the seats at the ballpark in the spring.
There are lots of cheerleaders on this board and lots of great advice. Just keep reading the posts...and hang in there. You can do it!