Using the resources God has blessed us with judiciously. This will obviously look different for each person: for some purchasing a slightly used BMW rather than one off the lot and for others saving up to by a well-worn Honda.
"1. Prudent economy; good husbandry or housewifery; a sparing use or appropriation of money or commodities; a judicious use of any thing to be expended or employed; that careful management of money or goods which expends nothing unnecessarily, and applies what is used to a profitable purpose; that use in which nothing is wasted. It is not equivalent to parsimony, the latter being an excess of frugality, and a fault. Frugality is always a virtue. Nor is it synonymous with thrift, in its proper sense; for thrift is the effect of frugality."
No matter where we are in the journey of life, it is easy to begin to envy the more lavish expenses of those who can genuinely afford it or become dejected because we don't stack up to a friend's frugality, rather than striving to become more prudent in our own "housewifery" and maintain the joy of frugality.
Joy seems to me to be the most important part of frugality. If the two do not stand together it will be difficult to avoid miserliness on the one hand and discontent on the other. But when they are united, joy brings contentment and peace to frugal endeavors.
By the way, for those who don't own a copy of Webster's 1828 dictionary, an online version is available here. :)