Weak at the knees

Pro Tip 1/3

Emotional Overwhelm

Use it to describe strong emotions that impact one's physical state, not just any feeling.

Seeing the Grand Canyon for the first time, I instantly went weak at the knees.

Pro Tip 2/3

Non-literal Use

It's a figurative expression; your knees might not actually feel weak.

During the intense horror movie, I felt weak at the knees even sitting down.

Pro Tip 3/3

Intensity Marker

Shows an extreme reaction, more than being just nervous or excited.

Hearing my song on the radio made me go weak at the knees with excitement.