Can't do 10 pushups, do what you can then revert to an easier version and do 10 more (example, let's say you can do 1 or 2, then go and do knee pushups and do 10 more).
Exercise releases chemicals and if you keep doing exercise you can get a pump, Arnold described it feeling as good as cumming - https://youtu.be/-xZQ0YZ7ls4
Arnold has said that he was selling himself as a bodybuilder and he would say a lot of things that were more promotional or propaganda to further his sport and his name. He explicitly says this in regards to the cumming comment