Hi Julie
Ive been walking for about 3 yrs, and Ive literally walked off the extra rear I had

Walking works for me, because I like it. I dont like going to the gym, or pulling out exercise tapes. So, if it works for you great, if not, try something else.
As for the being on your feet all day at work.....I had a job where I was at a dead run from the time I got to work, until I got home at night. It was an extremely busy and stressful job. I gained 40lbs there!!!! With the amount of lifting I did, you would think I would look like "Arnold Swart-hisface" So, depending on what your getting out of your job, you probably cant count it as exercise.
Since quitting my job, and living a fairly quiet life, with a 45 min walk almost every day, Ive lost the 40lbs. Go figure!