[1] Did you decide to quit sugar after reading one of David's books? If so go back to it and read the chapter about dealing with withdrawal symptoms.
[2] Have you removed all sources of temptation from the house and your work situation? If not do so now.
[3] You can use artificial sweeteners as a transitional device, especially in coffee for example. But re-read David's advice about going cold turkey.
[4] If your lack of resolve is an emotional issue rather than a physical craving, go see a psychologist to deal with it. This is what "comfort food" is about.
[5] &/or talk it over with a friend who has been through a similar experience, perhaps smoking or some other "addiction".
[6] Read the experience of others in the "Introduce yourself" page of this forum.
[7] Do some online research to see how beneficial it is to quit eating sugar - intellectual reinforcement I guess.
[8] DON'T GIVE UP! The struggle is REALLY worth the outcome.