The Lares Trek starts at around 3300 m and goes all the way up to the Andes water-shed at 4600 m. Even when you've overcome altitute sickness (it affected us on the first 1-2 days staying in La Paz), oxygen is low at this altitude, so it's very tiring. Petra made it all the way up with food poisoning. Respeto!! Very heroic.
One thing that is particular about the trek is that you often meet children that beg for food (bread) or toys. That's they don't actually beg for it, but they just stand in front of you and look at you like a dog until you give them something. Sorry, but I have to get a little political at this point. We can buy stuff that is valuable for them for practically no money, but I still very much dislike the begging, because it makes the fact obvious that Peru is a country with loads of young people and the useless government does not manage to care for them - neither it can properly feed its people, nor it makes sure that they get a proper education. Many people here in the remove regions do not speak spanish (just Quechua), although they theoretically learn it in school. And while the young children make a lively impression, the older ones appear dull to me. I find this very depressing and feel utterly sorry for this country, which could be much better off given that it has access to resources, farmland and coastline. Like many countries in africa this is an example of an ex-colony that has been left in a terrible state and doesn't get on its own feet.