listen to this song, Bring Sally Up - Moby

http://www.youtube.com/watch?v=uOEVIqcgz3Y

start off in the press up position, when they sing bring sally up, you go up, she says bring sally down you go down. Then stay down/up untill she says it again.

doesn't sound very hard but it kills your arms! see if you can finish the whole song.