DearMrs.Zhang，
Iamsorryinformyouofmydecisiontoresignmycurrentpositionasassistantinthiscompany.
Ienjoyworkingwiththepeopleintheoffice，becausetheyarekindandhardworking.However，afteramonth'swork，Iunfortunatelyfindthejobisquitefarfrommyexpectations.Firstofall，Icouldhardlybeartheextraworkandnightshift.Meanwhile，thesalaryisfarfromsatisfyingwhichcannotsupportmylargefamily.Whatismore，Ifindmytalentsarenotbeingmadeuseof.
Iamsorryforanyinconveniencecaused，andIsincerelyhopethatyouapproveofmyresignation.
Yourssincerely，