Debility

As I was in a state of extreme debility, I resolved to sail directly towards the town, as a place where I could most easily procure nourishment. […] I was ready to sink from fatigue and hunger, but being surrounded by a crowd, I thought it politic to rouse all my strength, that no physical debility might be construed into apprehension or conscious guilt.

Source: wiktionary

I was struck besides with the shocking expression of his face, with his remarkable combination of great muscular activity and great apparent debility of constitution

Source: wiktionary

At the mention of money Mrs Dibble was overcome with great debility, and wheezed, "I don't feel up to talking about money, matters just now, dearie. I think I better have a bit of a doze."

Source: wiktionary