different people resist different ways...
One way is to announce at work, "Hey, I know I'm fat. And I've decided to not eat sugar or white flour. I hope y'all can help me." For me, making such an announcement means that I'd be far too humiliated to eat in front of them again!
Another way to is keep emergency snacks on hand.
Another way is, as Donald said, to remind yourself of the reasons you're LCing.
Keep a list of all the symptoms you get on sugar--cravings, lethargy, etc. And keep a list of all the great things about LC. Review it often.
Do understand that there will always, always be a world of sugar out there. A WOL means we have to learn how to not eat it! Whatever strategy you choose, one of the above or another, choose it, make a commitment to it, and see if it works. If it doesn't work, you simply need a new strategy. Eventually, you'll find one that works for you!
For now, forgive yourself and move foward.