break (one's) neck
To put forth a great deal of effort. I've been breaking my neck trying to get a passing grade this semester, so failing by two measly points is incredibly frustrating. Don't break your neck trying to please these people—they'll never appreciate it.
break your ˈneck (doing something/to do something)
(informal) make a great effort: There’s no need to break your neck trying to get here by five. We can always wait for you.