Q:

100 push up challenge.

I've recently started the 100 push ups a day challenge. Currently I am on day 5 and I started having difficulties completing one hundred push ups. In order to finish up my "quota" of push ups, I set my knees on the ground and do it like that.
I was wondering if this by any chance is ruining the idea of the whole challenge? I am not not a complete beginner tho, I'd say beginner to intermediate. 
So far I haven't done nay rest days, should I take every 5th/7th or 10th day as a rest day? 

A:

I think the idea of the challenge ruins the idea of the challenge.
One of the points we try to hammer home, is that exercise breaks the muscle down, and then you build it back up stronger through eating well and resting well.
I think you should be taking every other day off, and see how that goes. That way, you give your chest and triceps some time to recover, and get ready for the next time.
EDIT: I knew this sounded familiar. Is doing push-ups every day healthy? Note also Dave Liepmann's answer, suggesting to not just workout two parts of your body, neglecting the rest. It tends to cause imbalances.

