Don't put off climbing Mt Kilimanjaro and don't think that you are too old. I went with my grown children and I am in my mid 50s, but I had the least problems with altitude or the physical attributes of the climb. I am NOT a jock, but in reasonable good condition.
Get your copy of the "Better Safari Photography" e-book at no charge, which pinpoints exactly what you need to know and do before, during and after your safari trip to improve your safari photography results whether you are a novice, intermediate or advanced photographer.