Painstaking
/ˈpeɪnzˌteɪkɪŋ/ adjective easyDone with great care and thoroughness, sparing no effort.
Restoring the old painting required painstaking work under a magnifying glass.
Memory Trick
Literally 'taking pains' — painstaking effort means being willing to endure the pains, the hard work, needed to get something right.