I started with one day fasts (miss breakfast + lunch) and then moved onto three day fasts (day 1=Friday, Day2/3=Sat and Sunday). That way most of your detox is on the weekend.
It's not ideal, obviously a 7+ day fast is better, but I work and my detox is bad enough that I can't walk into work on day 3+ and feel faint or take a 3 hour nap. So I did what I could and will be taking a 10+ day fast on my next vacation. Hopefully that will allow me to fast at work in the future.
Maybe you're in the same situation regarding work.