I hate limited cubical space at work. What kind of exercises can I do?

Muscle stretching. Muscle stretching and calf flexing under the desk is one.
Be Creative! There are many ways to improve exercise during work. Some include: taking stairs, parking farther away, walking to your favorite lunch spot, walking to a co-worker instead of using the intercom, hand weights at your desk, stretching exercises when at your desk, or walking for exercise around your work during breaks or lunch. Store dumbbells under your desk and use during breaks. Just keep active!