Coming from Australia - high altitude is unheard of! I also have pernicious anaemia so we were not sure if that was going to affect me, or make it worse. Ask your Dr, its odd but they give you medication for glaucoma (one of the side effects is it helps with altitude) take it for about 4 days beforehand. The Coco leaves work but they take app 3 days to kick in so if its a short stay then they aren't going to help much. Its an interesting experience, you are getting air and initally think what is the fuss, but we found our first night sleep was difficult, we both kept dreaming we were drowning, or suffocating! Make sure you pick a hotel with oxygen, just in case; we didn't use it, but it was comforting to know it was there. Novotel has it in their aircon (we never stay in chain hotels but that was one place I wished we had! Its a beautiful building). As someone else has said Machu Piccu is actually lower, and you really notice it, it makes the visit really easy. Our second night in Cusco was much more comfortable. Just expect to pant a little and be more tired than usual. My daughter walked the 4 day trail, she is an elite athlete but said it was hard due to the altitude, I caught the train, much more civilised!