To go to great lengths

To go to great lengths  - to work very hard to achieve something, to expend great efforts in trying to do something.

Example - "I went to great lengths to explain to him that he was not in any trouble"

Image - http://www.azquotes.com/picture-quotes/quote-i-am-an-eternally-curious-person-but-i-wouldn-t-go-to-such-lengths-to-know-what-it-is-matthew-carter-129-98-67.jpg