Hi Gail, and welcome to The Waiting Room - the virtual room where many of us await our own turns at valve surgery.
My situation is somewhat like yours. I have aortic stenosis, diagnosed about 5 years ago. Until then I had no clue that I might have a heart condition.
I am not a medical professional, so I can only relate to you anecdotal information about how my cardio is treating me. Once we determined that my stenosis was moderate to severe, we discussed exercise. I have been a recreational jogger for over 30 years, and the cardio told me that this sort of exercise is good for the heart, keeping it strong and potentially has allowed me to wait as long as I have for surgery. He advised not to "push it" and only go at speeds that are comfortable. A good warm-up helps, too. I am not on any restrictions as to heart rate, running speed, etc., just that if it doesn't feel good, slow down.
I have also been told not to lift heavy weights -- nothing over 40 lbs. I can do as many repetitions as I like, but nothing heavy. Heavy weights will raise blood pressure, and that is not good.
Also, I was warned not to participate in activities that have "high dynamic" range, where your heart is called upon to go from resting or slow pace to a dramatically higher pace instantaneously, like tennis or basketball. Because of this, I also stay away from the roller coasters. . .
Other than that, we are just watching and waiting.
My advice is to discuss all these things with your cardio. Every case is different, and you may have other circumstances that make your treatment different than mine. Above all, though, discuss it with the doc, learn all you can, then go back to living your life fully until you are told to do otherwise. Don't let them treat you like an 80 year old invalid without a good medical reason.
You've found the best place to learn from experienced people. Welcome!