Quoting Mama to A ♥:" My doctor told me 30minutes 3 times a week. And nothing intense. No running or jogging. Hes already had ... [snip!] ... (35lbs) and an extra 25lbs. But I have a long way to go. I have some 5lb weights, but that's all the exercising stuff I have. "
That sucks, I don't really know what to tell you. It's not impossible, but it is going to be hard to lose all the weight you want without being able to do more vigorous exercises. The problem with only being able to walk, is that there is no muscle confusion in that, and it becomes less and less effective as your body adjusts to it. I would either carry the weights or throw them in a backpack and carry them that way while walking. I know that my body would never drop 30 in 15 weeks without more intense exercises, but I don't know what your body is like, or how much weight you have to lose. If you are quite overweight then it will be a lot easier to get the weight off walking, but if you are closer to an average build it's going to be much harder.