It means that the thinker of these thoughts is living in a clean, wholesome atmosphere along with those who are determined and in earnest.

It means that they have caught the fervor of true life ...

a healthy, contagious fervor which permeates the blood swiftly once it gets a hold, and like electricity it vivifies and stirs the spirit with renewed energy _day after day, year after year_.

Once it wins us it will stick with us.

The success of those about us will shake our lethargic limbs and stimulate us to a desire to do as they do.