Losing weight is one of things that is mentioned in much of the medical literature as a possible remedy for GERD.
It is good that you are exercising and, as long as your doctor says your heart is able to withstand exercise, then you should go for it.
I think brisk walking is one of the best ways to lose weight as long as it is done on a consistent basis at least three times a week. Every day is even better. Just my opinion. Check with your doctor for sure.