At least for me personally that works best, whenever I try to remove or replace a bad habit with a healthy one and go cold turkey it usually just doesn't last more than a day or two and I just end up back on the train of bad habits, not sure what is the habit that you are currently trying to remove/replace right now but for instance in junk foods case people could start eating less and less junk food and replacing some of them with healthy ones here and there and gradually work their way up to a fully or mostly healthy diet.
it could be a solution but to maintain a healthy habit such as eating stuff that isn't bad for us, we need perseverance and that is the key to success for all the things we want to achieve in life, therefore perseverance in adopting good habits starting from work, like always greeting others