Variation of body mass

Hi all I am new here. Happy to hear from you how to keep the body mass constant and on the desired level. I want to keep 80 kg/183 cn but decrease fat from 22 to 19% and increase water and muscles mass accordingly. Any tips? I guess I will have to move a bit m. I have fitness room and pool at home but rather keep about 3000 sqm garden, grass and bush cutting, greenhouse care, compost treatment. It is not so healthy for my back though.