Hi, moonandstars --
There are probably statistics on this subject, but speaking strictly from my own experience, I'd say that exercise is as important as the right combination of meds. I wouldn't want to be without either. Over my 17 years with PD now, there have been times when I've gotten lazy or have been ill and skipped my exercise routine. Believe me, I felt the difference!
I understand your "not very sporty" comment. In my youth I spent very little time on sports or exercise, considering games a waste of time. Before my diagnosis, though, I discovered I enjoyed hiking. After the diagnosis I added workouts at a gym and stretching exercises at home. I still have to force myself to exercise, but I really feel the benefits in flexibility, stamina, and level of pain. For improvement in balance, I take Tai Chi classes. They are so enjoyable that I go eagerly rather than reluctantly!
When I was an instructor of English classes, I worked 12-hour days often, too. But I had already left the field of education when I was diagnosed; therefore, time allotment for exercise was not such a problem. If you learn a routine of stretching exercises and a series of exercises using weights, you can accomplish a lot at home either before or after work. Then perhaps you could add walking or tennis or golf or anything you like on weekends. Just suggestions . . . I know it's extremely hard to squeeze anything into a busy working person's schedule.
Best of luck,