A key mindset in frugality or simple living is to think in terms of utility rather than products. Our consumer-driven society is oriented to solving all wants by purchasing retail goods. The frugal mindset turns this on its head, and looks for means to ends. Buying something is but one of many solutions. It's push vs. pull. Marketing pushes: "you should be worried about identity theft and insurance solves that." Frugalers pull: "I need news. Talk to my neighbor? Blogs? Get a radio from Freecycle? Watch TV at the pub? If all else fails buy a newspaper or pay for cable."
This principle is manifested in a lot of bulleted money saving tips: brew your own coffee, buy used cars, use the library, and so on. The common thread is to identify the need, separate the core necessity (e.g. a book to read) from the unneeded frills (e.g. ability to keep the book permanently after it's read), and find the minimal solution that meets the core need.
When the "pull" mentality becomes an instinct these lists of tips become redundant because you automatically do this stuff as a matter of course. You might notice one or two clever ideas you hadn't thought of, but that's trimming around the edges. Detailed budgets become redundant as well. There's no need to monitor and ration your book expenditures (for instance) when you're already avoiding time-wasters and maximizing your library usage.
There's also a sense of calm that comes from acquiring things in response to only your own impulses and not the implied expectations of others. Those marketing messages work by instilling insecurities and providing solutions to them. Next time you see an ad, ask yourself "what is this ad designed to make me insecure about?" It's a relief to block out all those seeds for insecurity.
This all crystalized for me while watching a Linux machine install itself. Bear with me here. Historically Linux software had utilitarian, descriptive names. The Editing Macros are "emacs". The C Pre-Processor is "cpp". Free software isn't meant to be sold, so its name is just a utilitarian identifier. Indeed, the developers are sensitive about calling their work projects, never products. It's the "pull" mentality, and it's refreshing.