Another term you may know mindfulness as is "Insight" or "Vipassana" meditation.
Ajahn Chah, Jack Kornfield, and many others have written--and I have read--books on mindfulness.
My favorite one is Mindfulness In Plain English by Bhante Gunaratana because the narrative style is direct, simple, detailed, e.g. he talks about what to do if you encounter unpleasant memories from the past or get into a blissful state; what to do when your legs cramp and so on.
His message is delivered with a straightforward and gentle voice--no mention of precepts, gongs or bell ringing, et cetera which some people associate with meditation so much they cannot imagine meditating without these encumbrances, or to some "aids."
I like the advice about being mindful that runs pretty much like this: "Note the experience that comes up, a memory, a plan, a sensation, some kind of desire, then do not follow it; simple return to the breath. Even the 'wow moments,' same thing: Note them, don't get caught up in them, and return to the breath.
Later, Bhante G. and others talk about what to do off the meditation cushion to deal with the Five Hindrances, and the acronym R.A.I.N. helps me:
R - Recognize it (anger, for instance)
A - Accept it (don't repress, justify or deny it to yourself)
I - Investigate it (was the five course meal, for instance, really 'good' when examined, or did it lead to bowel distress; weight gain; a further need for heightened pleasure; loss of money, and so on.)
N - Non-identification (We are not the hindrances. They are part of "the passing show," all grist for the Mindfulness mill. Impermanent: They arise, peak, descend, disperse... and begin again... just as our own breath does.
There is more, and after choosing Vipassanas meditation from all the other types (so many!), I did get the Dhammapada again, which I'd had around 2000 but it didn't resonate for me as it does now. I read a bit from it most every day.
And Metta meditation can be done any time, anywhere:
I do it when I wake up, sometimes throughout the day, and before sleep; it lessens worry and helps me not speak sharply to my husband when I am in pain, and is leading to more growth. (This one I do no matter what, whereas I cannot always sit on my seiza bench or even in a chair and do Vipassana--right now my IT-band and lower back spasms are restricting that.)
Thanks @charlie.elliot for sharing this.