You might remember the meaning of the character 欠 with this easy mnemonic:
I heard that metal deficiency can be dangerous, so I've installed several magnets (⺈) in my son's room so he grows up to be a strong man (人) who doesn't lack (欠) important metals in his body.
Using mnemonics to remember the meaning of Chinese characters like has a huge impact on how long to learn Mandarin it takes.