mindful (adj.)

"that which feels, wills, and thinks; the intellect," late 12c., mynd, from Old English gemynd "memory, remembrance; state of being remembered; thought, purpose; conscious mind, intellect, intention," Proto-Germanic *ga-mundiz (source also of Gothic muns "thought," munan "to think;" Old Norse minni "mind;" German Minne (archaic) "love," originally "memory, loving memory"), from suffixed form of PIE root *men- (1) "to think," with derivatives referring to qualities of mind or states of thought.

Meaning "mental faculty, the thinking process" is from c. 1300. Sense of "intention, purpose" is from c. 1300. From late 14c. as "frame of mind. mental disposition," also "way of thinking, opinion." "Memory," one of the oldest senses, now is almost obsolete except in old expressions such as bear in mind (late 14c.), call to mind (early 15c.), keep in mind (late 15c.).

Mind's eye "mental view or vision, remembrance" is from early 15c. To pay no mind "disregard" is recorded by 1910, American English dialect. To make up (one's) mind "determine, come to a definite conclusion" is by 1784. To have a mind "be inclined or disposed" (to do something) is by 1540s; to have half a mind to "to have one's mind half made up to (do something)" is recorded from 1726. Out of (one's) mind "mad, insane" is from late 14c.; out of mind "forgotten" is from c. 1300; phrase time out of mind "time beyond people's memory" is attested from early 15c. 

word-forming element attached to nouns (and in modern English to verb stems) and meaning "full of, having, characterized by," also "amount or volume contained" (handful, bellyful); from Old English -full, -ful, which is full (adj.) become a suffix by being coalesced with a preceding noun, but originally a separate word. Cognate with German -voll, Old Norse -fullr, Danish -fuld. Most English -ful adjectives at one time or another had both passive ("full of x") and active ("causing x; full of occasion for x") senses.

It is rare in Old English and Middle English, where full was much more commonly attached at the head of a word (for example Old English fulbrecan "to violate," fulslean "to kill outright," fulripod "mature;" Middle English had ful-comen "attain (a state), realize (a truth)," ful-lasting "durability," ful-thriven "complete, perfect," etc.).