As a competitor, Navratilova was a fantastic athlete who was always well prepared for her matches. Her conditioning will no doubt be helpful for her in the climb, as she has never been above 12,000 feet before, although she does call the Kili trek "just a basic hike." The fact that she lives in Aspen, Colorado, and is use to altitude already, will be a benefit as well.
The goal is to raise 100,000 euros, or roughly $134,000, through her donations page, which can be found here. Reportedly, more than half of that sum was already raised before Martina ever left for Africa, which bodes well for her reaching her goal.
Over the course of the next week, the tennis great will be hiking up the mountain, and of course she's carrying her trademark racquet and a few tennis balls with her. While she doesn't expect to play a match at the summit, she is going to hit those balls off the top of Kilimanjaro just to see how far they'll fly. My guess is they hit the Serengeti from all the way up there!