Kakoda would be a huge challenge! I am told that the trek to Base Camp only requires reasonable not super duper fitness level as long as you pace yourself and do some hill training leading up to it. For me the big challenge will be believing in myself and my capacity to do something out of my comfort zone! One thing I will say is that since I started planning for this I already feel stronger (scared but hey it can't be as scary as losing a breast and having to have chemo!) and more motivated to be active. I think it's definitely taken my mind away from dwelling on what if ....