You can but 10lbs a month, every month, is a huge ask.
Personally, I would aim for a lower amount - maybe another 40 - but work very hard, and it could be more. That way if (sorry, WHEN) you reach or surpass 40, you'll feel so victorious. If you aim for 90 and make even 'only' 80, or even 89, you'll feel cheated.
Either that or not have a fixed figure, that can get really pressurizing in a bad way, but celebrate, say, every 10lbs in a big way, and just see how many celebrations you can get in, rather than specify a number.
Oh, and congratulations on the 40!!!!!
Dukan & divin'.....