The lap band is what takes away the physical ability to intake as much food as you once ate. But the desires and old habits can still be there.
This is partly why exercise is so important.
I had my surgery on 4/9/07 and I have lost 65 lbs so far. I am firmly convinced that it is in large part because of my exercise regimen. I walk/run on the treadmill 5 days a week, then I lift weights 5 days a week and on m-w-f I go back to the gym a second time during the day to work out some more. There is no question in my mind that without that regimen, I would probably have lost only 30-40 lbs by now.
But what is even better is how great I feel. It's incredible to me that I have so much energy.
So I do absolutely encourage and recommend lots of exercise. You will see results. I guarantee it.