I'm glad to hear you're a walker. In my view, after surgery the speed isn't nearly as important as the movement. You're operating your lymphatic system when you walk, which helps you heal by moving the lymph along. This reduces swelling and inflammation.
At this point, you want to stay capable, but extra exercise or heavy exercise is more apt to do harm than good. Walk, but don't push yourself. You're going to love walking again after your heart starts to recover.
If I wasn't clear in the other thread, you will feel much better after the surgery. It may not be instant, but you will definitely be glad you did it. It should help your situation tremendously.
I know you're concerned about how the surgery will go. But you'll do all right. It will go faster than you think. If you're confident in your surgeon's abilities, you can let go a little, and leave it up to him. Somewhere around the time you actually go in, you may just find yourself giving over the responsibility to them anyway, and it is a tremendous load off your mind. It creates a great peace within you.
As far as looking forward, males should know that "pelvic steal" is a common side effect of advancing valve disease, and that it usually goes away after successful valve surgery.
Best wishes,