Can’t say no to sweet/treats when offered

Dear Brooke,

Thank you for your work! I am what most people would consider a healthy eater, I pack myself healthy options for my meals and am typically good at not buying much junk food HOWEVER at work there are constantly treats up for an offer! I have a hard time saying no when I’m directly asked or even when the treats are just there on the table. It’s frustrating because I find I go off track on my healthy eating plan a lot simply because I’m constantly tempted to eat unhealthy things and I always seem to give in. How do I stop this? Thank you in advance!