That's not the lexical definition of effort.

It's a stipulative definition that allows the author to reach a conclusion that's inherently provocative when read by people who are using the lexical definition.

> Therefore, putting effort beyond what is needed, by their definition, is excess and should be avoided.

By qualifying with "beyond what is needed" you've made it clear that you're using the lexical definition of "effort". I think that should drive home how absurd the author's definition of "effort" is. They've been careful not to make it a clearly circular definition (effort = effort beyond what is required) but they are awfully close.