Generally, our attitude is that we always want to protect our own territory first. We want to preserve our own ground - others come afterward. The point of this slogan is to change that attitude around, so that we reflect on others first and on ourselves later... You also try to get away with things. For instance, you don't wash the dishes, hoping that somebody else will do it. Changing your attitude means reversing your attitude altogether - instead of making someone else do something, you do it yourself.
Then the slogan says 'remain natural' which has the sense of relaxation. It means taming your basic being, taming your mind altogether so that you are not constantly pushing other people around. Instead, you take the opportunity to blame yourself... Instead of cherishing yourself, you cherish others - and then you just relax. That's it. It's very simple-minded.
From Training the Mind & Cultivating Loving-Kindness by Chogyam Trungpa , copyright 1993 by Diana Mukpo.
(Official Chogyam Trungpa Website)
Published by arrangement with Shambhala Publications, Inc., Boston.
This site provides an on-line database of commentaries on the Tibetan Buddhist meditation practices of lojong (Mind Training) and tonglen.