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.

see under break one's back.

To hurry as fast as one can, to proceed with reckless speed. The same idea is conveyed by breakneck pace, the word breakneck dating from the sixteenth century. At that time, however, to break someone’s neck also meant to overpower or overwhelm them. This was Sir Geoffrey Fenton’s meaning when he wrote, “To breake the necke of the wicked purposes and plots of the French” (The History of Guicciardini, 1579).