Welcome! As you walk more, and stick to a diet of fewer calories, you will be ABLE to walk more - it will be easier for you. Your muscles will strengthen and you'll be moving through space with less weight, so it will get easier.
Yeah, weight loss will evaporate if you don't work on maintaining the loss by continuing to eat less and move more! But you CAN do it. There's a great DVD series that is sold in many stores... here it is on amazon.com:
Amazon.com: Best Walking DVD's