Just came back from the GE and besides the gerd, i also have an intermittent hiatal hernia. I am very athletic and used to do high intensity training and the doctor told me that won't be possible anymore.
If you dont have hiatal hernia, you can probably do whatever type of sports you want. You could probably do yoga if you've been diagnosed only with gerd.
Gerd gets bad when you do aerobic stuff like jumping or moving your arms fast and twisting your torso. At least for me that's when it got bad. Also when you exercise, breathe in your abdomen and not in your chest.