Most people that understand things like euphemisms such as “it's so easy that even a monkey can do it.” For those that don't know what that means, a euphemism used like that signifies that a task or activity is so easy to do that it's almost impossible to mess it up or that doing such a task is not that complicated. This euphemism can be used for many things. One such thing would be getting into shape which can be tacked onto many different issues such as health, fitness, and so forth.
A recently uploaded video really gives the meaning of “it's so easy that even a monkey can do it.” In this video, though it's only a little over a minute, has a monkey doing push-ups and sit-ups like it's nothing. The monkey is doing such exercises like it's nobody's business. At the end, the monkey looks all relaxed and seemingly hasn't even broken a sweat. This can be perceived as something motivational as well for those that complain that they cannot get into shape and so forth.
In this respect, this monkey may have put many humans to shame when it comes to doing simple push-ups and sit-ups. This also plays on the scientific theory of humans evolving from apes.