To change ones life, start immediately, do it flamboyantly, no exceptions.

Gradual change fails more often than it should, because a small adjustment is easy to reverse and easy not to notice. A decisive one creates a clear before and after, which gives you something to defend and other people something they can see. The no exceptions part does most of the work, since a rule with one allowance quickly turns into a preference.

If the gentle version has failed several times, try the abrupt one. Start today rather than Monday, and make it visible enough that going back would require an announcement.