It's very simple. Just a short training program to get you from where you are - if you are over 50 and you can do more than 20 push ups you are about in the middle of the fitness range - to 100 push ups (press ups we English say) in 6 weeks of training. Nothing needed except yourself and the floor.
I like the idea, and the challenge. I'm pretty fit for a 60 year old and a weightlifter but 100 push ups is a serious number and I'm way off... 30 is about my current mark. The fact is that push ups sound simple but the exercise uses a range of muscles including those in your core that are very important as you get older (back pain etc...). Well worth the effort to strengthen them.
So I'm taking up the challenge and will be reporting it accordingly.