Enervate (verb)

1. To weaken or drain the energy and strength of.
2. To make feeble or ineffective.

Origin:

From latin enervatus, past participle of enervare "to weaken, deprive of strength" which comes from e- "out" + nervus "sinew, nerve".

Examples:

1. The long hours at work enervated him and he could barely keep his eyes open.
2. The heat enervated the players and they struggled to perform.
3. The disease enervated her body, leaving her unable to walk.
4. The constant criticism enervated his confidence.
5. The budget cuts enervated the department's ability to function properly.