I Am In Good 'statistical' Shape. However, I Have Become

I am in good 'statistical' shape. However, I have become weakened to the point that I can walk only about 50 feet. Five months ago, I could do probably walk twice as far-maybe three times as far, usually more, without becoming winded. I have been declared to be 'home-bound.' I am now just about a prisoner in my house. I can't drive my car-per doctor's orders. I can be driven to 1] church, medical care. and hair-cut. What are my options to return to strength and endurance?