Work your fingers to the bone
Definition 1 of 1
Pro Tip 1/3Metaphorically Speaking
The phrase is not literal; it's not about actual fingers or bones, but about extreme effort in work. 
She's working her fingers to the bone studying for exams.
Pro Tip 2/3Intensity Emphasized
Use it to express a very high level of effort, almost to the point of exhaustion. 
During the harvest, farmers often work their fingers to the bone.
Pro Tip 3/3Not for Casual Use
This phrase is intense. Don't use it for regular daily tasks or light workloads. 
While preparing for the product launch, the team worked their fingers to the bone.