One way to make a waking program more viable is to incorporate other activities of interest to you - do it in an interesting environment, see something interesting. Tour a Civil War battlefield or go bird watching, etc. - whatever floats your boat.

I always like mixing walking or hiking with bike riding. You burn the same amount of calories per time unit in each activity, but you go about three times further on the bike. How about commuting to work on the bike? Is that feasible?

Can you stash healthy food at work rather than rely on the cafeteria?

Personally, I have had better success with gradual reduction in calories rather than s sudden change. I have also found it helpful to weight myself regularly, but not often.