This phrase is a metaphor, suggesting a tide is at its lowest point, reflecting a temporary state. Her motivation was at a low ebb, much like the receding tide.
Pro Tip 2/3
Temporary State
Used to emphasize that the situation may improve, as 'ebb' implies change over time. Though at a low ebb, he hoped for a turnaround.
Pro Tip 3/3
Subtle Emotional Tone
The phrase adds a layer of empathy when discussing someone's difficulties. Seeing them struggle, I knew their energies were at a low ebb.