I need to lose a serious amount of weight, but every single time I try to exercise, I have a panic attack. Walking is okay, but the second I stop walking ..I feel like soo dizzy and I will feel lightheaded and like I will fall. I try to exersice and it frustrates me badly that I feel anxious even while trying to do something good for my body. Does anyone else experience this? Advice? Tips on how to manage that.?