At the time of this writing (2008) I am 50 years young, not quite athletic but very far from being a couch potato. At 73kg (160 lbs) and a height of 183cm (6' 0" ft) I don't suppose you could all me overweight. The only sports I've been doing for years are my semi-regular workouts on a stationary bicycle / elliptical trainer. I also go to weekly Yoga courses to help keep my back in shape as well as to maintain flexibility.
After doing well on a stress electrocardiogram test last year I felt it objectively confirmed that my cardiovascular system was not going to let me down.
A day-hike in the Alps a half year prior to Kilimanjaro confirmed that my leg muscles needed a lot of work. The hike itself was great... I just couldn't walk normally for the following 4 days due to the pain in my calf muscles.
What to do ??
Hike, hike & hike some more...
I started out by extending the intensity of my share of the dog walks until the dogs started to think I was nuts... Sorry guys...
I then began adding a lot of flatland hiking around our rural area (always with a 9kg (20 lb) backpack). Living in Germany's Rhein-Main region I was able to add weekend hikes in the nearby Taunus "mountains" just to the northwest of Frankfurt. I feel that these hikes were the most important because of the muscles being used in ascending and descending. From a convenient parking area at 356m (1170 ft) I hiked to the top of the "Altkönig" (798m/2620ft) 8 times and to the top of the "Grosser Feldberg" (878m/2880ft) once, several days before leaving for Tanzania. These peaks are certainly not quite in the same league as "Kili", but it was the best I was able to do here in the Frankfurt region.
All in all I hiked around 300km (190miles) in the 8 weeks prior to leaving for Kilimanjaro. It was also very enjoyable as well !
Preparing in the middle of winter meant I did most of my hiking in very cold, icy and sometimes snowy, windy weather.
Not yet being an experienced hiker these hikes gave me great opportunities to try out all the gear I had needed to purchase. I had never worn polypropylene hiking clothes before (i.e. underwear, t-shirts, pants etc.). Believe me, you'll never want to wear cotton again !!
I was also able to test my photographic equipment (as well as my gloved and ungloved shutter finger) at freezing temperatures well below -7°C (20°F).
Did all this hiking really prepare me well enough?
YES, physically as well as mentally. My legs ended up holding up very well. The toughest part for my legs though proved to be the descending leg of the route. Your knees take quite a load during the very long continual descents. The obligatory hiking sticks are definitely worth their weight in gold at this point.