I leave for a tour of the Galapagos and Macchu Picchu in 2 weeks. I am getting along in years (61) and not in the best physical shape. I do walk regularly and am looking forward to the hikes listed on the tour. Several are rated as easy, 2 are intermediate and one is difficult. I am assuming I can do the easy, not to sure about intermediate and worried about difficult. Can anyone give me some idea of what they are like for someone my age?