It is very difficult to attain Self abidance, but once it is attained it is retained effortlessly and never lost. It is a little like putting a rocket into space. A great effort and a great energy are necessary to escape the earth's gravitational field. If the rocket is not going fast enough, gravity will pull it back to earth. But once it has escaped the pull of gravity it can stay out in space quite effortlessly without falling back to earth. (From Annamalai Swami)