Related Clues:

• Lacking energy
• Listless
• Wiped
• Ready to retire
• Exhausted, as one's strength
• Ready to rest
• Worn-out
• Very tired
• Pooped, perhaps
• Lacking pep
• Physically and mentally fatigued
• Depleted of energy
• Drained of strength
• Made less vital
• There's no rest for them (with "the")