I am a 43 yoa woman that found out a year ago that I had a...

I am a 43 year old woman that found out a year ago that I had a severe mitral regurgitation. I have extreme fatigue to the point that I have no energy when I get home from work and if I sit for just a few minutes I could just fall asleep without hesitation. I often have a discomfort in my chest and palpitations, but was told by a surgeon that nothing has changed in my condition for the year so I do not need surgery, even with my symptoms. They concluded that I must exercise more and go in and do a exercise treadmill test. Wouldn't exercising more make me more fatigued? And how do I know how severe is severe? Is it not better to fix normal size heart than to wait until damage starts to appear?