Possible Clues:

• Lose impetus
• Dismissed old fellow leading second eleven to finish exhausted?
• This will happen if you fail to refill kettle or lose one's energy
• Lose enthusiasm, as one deprived of heat and water could
• Tire
• Have no motive force left
• Lose impetus, like Awdry's Thomas?
• No puff left
• Exhaust oneself
• Lack the energy to continue