Can you suggest a rigorous and effective workout I can do while I'm at work?

Workout. A body weight high intensity interval program can be done with with minimal room and no specific equipment for very little time everyday. Dr. Al sears a anti aging physical medicine doctor has a great program call pace that you can do at home.
Exercise at work. Depends on what is available. Is there an exercise room at work? Is there a place where you can jog and run? It would be good to do a vigourous workout that raises your heart rate and makes you sweat.
Home exercises. This is a unique question... I might suggest that you work at a pace that raises your heart rate. You may also want to invest in some cuff weight that you can attach to your ankles or wrist. When stationary, do calf raises. When moving from one room to the next try to skip, jump, or lunge from point a to point b. With all this said, don't forget to stretch :) hope this helps.