Just like you said, consistency is the only thing that can help you achieve your dream of doing 50 or 100 push-ups in a set in this push-up challenge. But since you have yet to do 50 push-ups in a set for the first time, I will advise you to set your mind to doing 50 push-ups in a set first before you do 100 push-ups in a set so that you can build up the strength that would help you achieve 100 push-ups in a set. And for you to be able to do 50 push-ups in a set, you need to maintain 40 push-ups in a set for a long time to gain the stamina that would allow you to push to 50 push-ups in a set.