I think it comes across as just a general fitness challenge rather than anything directly relatable to steem. It's a great idea to get people active but the trick is getting them to see what steem is about.
Maybe in these videos everyone is sharing, there could be an animation about steem with a powerful message about steem? "Engagement that pays" or something like that (someone with copywrite experience can probably help).
At the moment, it's just people doing push ups for 77 days and a steem hashtag so maybe a requirement of the challenge can be to mention steem in the video in a nutshell (no more than 10 seconds talking about it). I think that would be more powerful.
But really some great feedback and comments from everyone here already.