Grace is attained by God working through humanity. Just like the Incarnation, when He took humanity upon Himself in order to transform it.
That's what sacraments are - God working through his creation in order to transform it.
It all makes sense if you think about the Incarnation for a minute.
Your religion made that up and you are just repeating it...The definition of grace is given by the scriptures, not your religion...
There is no working whatsoever whether it be God or mankind...Grace is so free, no one even has to ask for it...