A high school teacher wanted to demonstrate a concept to his students. He takes a large-mouth jar and places several large rocks in it. He then asks the class, "Is it full?" Unanimously the class replies "Yes".
The teacher then takes a bucket of gravel and pours it into the jar. The small rocks settle into the spaces between the big rocks. He then asks the class, "Is it full?" This time there are some students holding back, bust most reply, "Yes".
The teacher then produces a large can of sand and proceeds to pour it into the jar. The sand fills up the spaces between the gravel. For the third time, the teacher asks, "Is it full?" Now most of the are wary of answering, but again, many reply, "Yes"
Then the teacher brings out a pitcher of water and pours it into the jar. The water saturates the sand. At this point the teacher asks the class, "What is the point of this demonstration?"
"No," replies the teacher, "The point is that unless you first place the big rocks into the jar, you are never going to get them in."
The big rocks are the important things in your life--your family, your friends, career, your personal growth. If you fill your life with small things--as demonstrated by the gravel, the sand, and the water--you will never have the time or the space for the important things.
When you are hassled because there is not time, remember the story of the Big Rocks and the Jar.