virtue

Juvenal's mens sana in corpore sano, a "good idea" worth quoting at length:

It is to be prayed that the mind be sound in a sound body.

Ask for a brave soul that lacks the fear of death,

which places the length of life last among nature’s blessings,

which is able to bear whatever kind of sufferings,

does not know anger, lusts for nothing and believes

the hardships and savage labors of Hercules better than

the satisfactions, feasts, and feather bed of an Eastern king.

I will reveal what you are able to give yourself;

For certain, the one footpath of a tranquil life lies through virtue.