The word mindfulness has been colonized by an industry, and the books that get recommended under that banner are usually either instructions for a meditation technique or arguments for why the technique is good for you. Both types are fine and neither is what I'm recommending here. The books below are about attention — what it means to pay attention, what gets in the way, and what becomes visible when you finally manage it. They are better as starting points than any guided meditation app because they give attention a subject rather than just a technique.
The most direct entry point is Tao Te Ching in Stephen Mitchell's translation. The original text is roughly 2,500 years old and concerns itself with a concept that does not translate cleanly: the Tao, usually rendered as The Way, which is simultaneously the underlying pattern of reality and the correct mode of engaging with it. Mitchell's translation is a free rendering — he worked from existing translations rather than directly from the classical Chinese — and it reads like someone thinking clearly about how to live rather than like a scripture. The core idea most relevant to mindfulness is wu wei, non-doing: acting in alignment with what is actually happening rather than imposing a plan on top of it. Each of the 81 chapters is short, readable in a minute or two. The right way to use this book is slowly — one chapter, then a day, then another chapter.
Alongside the Tao Te Ching, The Way of Chuang Tzu, in Thomas Merton's free interpretation, extends Taoist thought into territory that is stranger and funnier. Chuang Tzu was a Taoist philosopher who wrote in parables and paradoxes — the stories resist direct interpretation by design, because the point is to sidestep the habitual categories of the analytical mind. Merton was a Trappist monk and a serious student of Eastern philosophy, and his version preserves what is most disorienting about Chuang Tzu: the way the stories make you feel that the conventional way of seeing things is arbitrary and could be let go. This is, practically speaking, one of the most useful things a book can do for a beginning practitioner.
For a more systematic treatment of attention as practice: Meditations by Marcus Aurelius, in Gregory Hays's translation, is a daily practice manual disguised as a philosophical journal. Aurelius was a Roman emperor and a committed Stoic, and his private notes — never intended for publication — are the record of a man returning, day after day, to the same basic reminders: here is what is actually in your control; here is what you are choosing to attend to; here is what you are avoiding. The Stoic understanding of mindfulness is not about relaxation or stress reduction — it is about accurately perceiving the situation you are actually in, without the distortions of fear or desire. Hays's translation is direct and modern and cuts through the Victorian heaviness of earlier versions. Read it in the morning.
The most radical account of sustained attention I know of in literature is Pilgrim at Tinker Creek by Annie Dillard. Dillard spent a year observing a single creek in Virginia's Blue Ridge and produced a book that is not, in the usual sense, about nature. It is about what happens to perception when you commit to looking at something very hard for a long time. The specific observations — the praying mantis eating, the frog deflating as she watches, the light on water at different hours — become the occasion for encounters with reality that are genuinely destabilizing. Dillard does not smooth over what she sees into something reassuring. The mindfulness she models is not calming; it is clarifying, which is a different thing entirely. For beginners who want to understand what careful attention actually looks like in practice — not as technique but as a way of being in a place — this book is essential.
A Sand County Almanac by Aldo Leopold is organized as monthly observations of a Wisconsin farm across one year. Leopold was an ecologist and the book is in part a scientific record, but its real project is the education of perception — learning to see what is actually present in a landscape rather than what you expect to find. The January chapter describes tracking a skunk through snow and reading the night's events from the marks in the ice. The August chapter describes the sound of geese navigating by stars overhead. Leopold's attention is not meditative in the Buddhist sense, but the capacity it models — noticing what is actually there, not what you project — is the same capacity mindfulness practices are trying to cultivate. The land ethic essays at the end are a philosophical account of what attention to the natural world makes you responsible for.
Finally, Flow by Mihaly Csikszentmihalyi is useful here as an account of what full attention feels like from the inside. Csikszentmihalyi studied people across cultures who reported states of deep absorption — athletes, surgeons, chess players, musicians — and found consistent structural features: the activity required full engagement, challenge matched skill, feedback was immediate, and the self temporarily disappeared. This is not different from what contemplative traditions have described as concentrated attention; Csikszentmihalyi is describing it from a psychological research perspective. For beginners who find meditation instructions abstract and disconnected from their actual experience, this book provides a different entry point: here is what the state you are trying to cultivate actually feels like, and here are the conditions that produce it reliably.
The common thread: all of these books treat attention as something that can be educated — that the quality of your attention is not fixed, that it responds to practice, and that the practices worth engaging in are those that put something real in front of you and ask you to look at it without flinching. Start with the Tao Te Ching. See what the others open from there.