Why is it so hard to stay on track?

So I need to try to figure out why I have start all over again. I need to re-think the process and see that I am achieving just small weight loss and even though that is better than nothing, it is not where I want to be at.

I think clean eating is so hard. We have so many not healthy options at work, there is birthdays and lunches and sweets. And there is stress, and I eat more when I am stressed out. It is a cycle, and I need to move forward and not to stay there anymore.

Starting is not the hard part. The first couple of days, even weeks it is easy, but then life gets on the way and I either stop losing or gain a little bit more back. I need to figure out a way to get back on track and continue losing.

I am going to be back to portion control and low glycemic index foods. I think I need to keep my intake journal. I cannot wait for another 2 week challenge. I feel more motivated when I have to report to someone.

The good news, I have not have diet soda since January and that is huge for me. Now I need to concentrate on getting back on track.

Tell me how do you stay on track? Any advice would be appreciated. 
Have a great week!