Fig.: to work very hard

I sweated blood to start and build up my little business, so I won't let anyone take it away from me

Ho sputato sangue per avviare e far crescere la mia piccola azienda, perciò non permetterò a nessuno di portarmela via

To have finished building the house by themselves in their spare time, made them feel very proud because they had sweated blood every step of the way

Erano molto orgogliosi di essersi costruiti una casa da soli nel loro tempo libero, anche perché hanno sputato l'anima per finirla

The expression refers to Christ's agony in the Garden of Gethsemane: "And being in agony He prayed more earnestly; and His sweat became like great drops of blood falling down upon the ground" (Luke 22:44)