What is Spent?
There is nothing left in the tank — you have used everything you had. The well is dry and functioning is happening on fumes. This is not laziness but the natural consequence of prolonged output without adequate recovery.
When you might feel spent
Spent is a specific form of burned out, which itself is a type of depleted. You might experience this feeling in situations where depleted is present, particularly when the circumstances align with the nuances that define spent.