What is "strenuosity"

Usage examples of "strenuosity".

From serene wife, Edith, to brilliant daughter, Alice, to the various Norn-like sisters, the ladies were never strenuous, unlike the menfolk, who never ceased to give unconvincing imitations of Theodore Roosevelt’s strenuosity and superb manliness against every odd.

They've had so dang much strenuosity all their lives, and then the climate's against violent effort, either mental or physical.