Etymology: Actually an ideograph of a bent figure with long hair, both associated with age. Age is associated with careful thought / consideration.
This is now hard to decipher.
Suggestion: Earth with s.t bent and half-buried in it, meaning old-age (i.e. ready for the grave).
Mnemonic: BENT OLD MAN CONSIDERS HIS GRAVE WHILE HALF-WAY INSIDE IT!
参考 (sankou) reference
考え事 (kangaegoto) concern
(Based upon Henshall, 1998)