It should reflect how you arrived at your professional goals, why the program is ideal for you, and what you bring to the program. Dont make this a deadline tasknows the time to write, read, rewrite, give to a reader, revise again, and on until the essay is clear, concise, and compelling. A hint: you may find yourself writing a good, specific sentence right after a general, meaningless one. If you spot that, try to use the second sentence and delete the first. When did you become interested in the field and why? What path in that career interests you right now? Brainstorm and write these ideas out. The program. Why is this the program you want to be admitted to?
Again, doing research on the program may reveal ways to legitimate even your most superficial and selfish reasons for applying. Yourself. What details or anecdotes would help your reader understand you?