Rock,pebble & sand
Jar filled with rock can take extra pebbles still and sand can be poured on top.
Rocks are important things like family, pebbles are like jobs, sand is small stuff in life. If you fill your life jar with either sand or pebbles first there is no space for important rocks of life. Serenity is letting go of things you cannot control having the courage to change what you can. Hope this helps.