Blood, sweat and tears
Definition 1 of 2
Pro Tip 1/3Emotional Intensity
Conveys more than just hard work, but immense personal investment and determination. 
Winning the championship required her blood, sweat and tears.
Pro Tip 2/3Not Literal
A metaphorical expression, does not mean actual blood or tears. 
His first novel took blood, sweat and tears to complete.
Pro Tip 3/3Serious Endeavors
Used for tasks that require significant effort, not for simple or easy tasks. 
Becoming a doctor involves blood, sweat and tears.