Margaret Mead says it is easier to change our religion than it is to change our diet.
And it is so hard to change our diet because it is ruled by our appetite.
So although we can't change our appetite by an act of will, we can sculpt our appetite. We can sculpt our appetite into an appetite we would like.
In a way sculpting our appetite is a bit like meditation - no one can meditate by an act of will, but by repeating other things, the meditative state can creep up upon us.
So if we wish to change our diet from SAD (standard American/Australian diet) to healthy fruit and vegetables in green smoothies with a side dish of steamed fish, we can only approach it indirectly.
So we have a repetition of two days. First day we have green smoothies and fish, and the second day, we have anything we like. And on the third day we have green smoothies and fish. And on the fourth day we eat anything we fancy. And we do this repetition for eight days.
And most important, at the end of every meal we see how we feel. If we feel better after the green smoothies, we keep making the green smoothies. And if we don't, we stop.
In this way we slowly sculpt our appetite with green smoothies and before we know it, we have moved from SAD to delicious.