Today I did 862.
It's a mental and physical challenge. I do seven press-ups every 30 seconds for the first 50 minutes, then eight press-ups every 30 seconds for the last ten minutes (with an extra two thrown in at the end, which was all I could manage).
Getting to the thousand is a going to be tough. I need to do over 16 press-ups per minute, which results in less recovery time.
It's hardly a fun filled or interesting way to spend an hour. But then I have 16+ hours in cold water to look forward to. This part should be a doddle in comparison.