0. Frugality
The internet calls this FIRE (Financial Independence / Retire Early) or ERE (Early Retirement Extreme) but I just call it responsible living, or getting one's house in order, or growing up.
Mr. Money Mustache (Pete Adeney) jokingly calls it Mustachianism (referring to the size of one's money mustache or nest egg).
Frugality is about more than money. It is about efficiency, avoiding waste. It is about avoiding being conned. It is about organizational skills. It is about synergy, or killing two or three birds with one stone, such as walking to get groceries and exercising at the same time. It is about recognizing that the best things in life are free, like time at the park, or a walk on the beach, or a hike, or visiting a public library weekly and bringing home a crate of books to read as a family. It is about being in a place to take care of oneself so one can lift others.
It is about human psychology and knowing how to avoid the consumer mindset (believing that purchasing more stuff will make you happier, or believing that others care at all about your car, house, clothing) and avoiding the trap of the rat race (selling your soul to your employer for some eventual, theoretical, never-appearing return). It is about being in the present and enjoying what you have, avoiding the hedonic desire for more, more, more. It is about doing pushups at home or at the park, and running or biking, instead of joining a gym. It is about doing your own yard work, instead of paying landscapers to work on your yard while you drive an airconditioned car to an airconditioned gym, all to run in place on a literal treadmill.
It is about filling one's time with wholesome, inexpensive, effortful pursuits that are ends in themselves and have positive net benefits, such as home cooking, gardening, home improvement, making things, learning things from library books, playing a musical instrument, etc.
Examples of wastes of time and resources would be: endless clothes shopping when one's wardrobe is currently sufficient—not to shame fashionistas, just a reminder to donate what you don’t use and don’t need; buying knickknacks or trinkets that collect dust, instead of collecting photo memories; eating out too often, overeating or wasting food, instead of collecting recipes and trying to learn how to cook new things; watching too much (paid or unpaid) entertainment with little educational or spiritual or aesthetic value—the definition of this is up to you; and on and on.