sap (someone's) strength

Translations
ослаблять силы (кого-то)
The illness sapped his strength over time.
Болезнь со временем ослабила его силы.
Definitions
To sap someone's strength means to gradually weaken or drain their energy, vitality, or resolve, often through persistent stress, pressure, or fatigue.
Words
strength

noun
сила
sap

verb
истощать