As a health counselor, I wholeheartedly promote adding more nutrients to a diet versus dieting. And we may apply this idea to every aspect of our lives:
Crowd out the relationships that do not serve you with those that do.
Add more steps (walking, running, stairs, etc.) to be a little less sedentary today.
Read 5 minutes more from an inspirational book to reduce internet-browsing time.
While it's possible to just quit a bad habit all at once, we may eventually say, "just kidding!" and return to things, people, or places that drain us rather than lift us.
Diets don't work, food- and life-wise. Instead, crowd out--gradually. We'll not only feel physically lighter, but mentally and emotionally better.