You have work  in a healthcare setting for 5 years and you have always enjoy coming to work 4days in week. now due to personal reasons you wan to cut your work days to one a week, write an emotional letter to management, thank them for an amazing  conductive environment,the educational traing they always  provide . let them know how excited it was to work for them and express hope that you will come back in the future,  end you letter with words , I will always be an ambassador to this company that help shape me. or some words of gratitude  
one page is okay