Here you want to make the claim that youāre a good candidate for this particular program.
Avoid āIāve always loved Historyā introductions; thatās assumed at this level.
Focus on the periods, themes, and questions that drive your passion for Historyāfor example, āIām interested in exploring the interplay of class and gender in industrializing European societiesā or āIād like to examine American foreign policy vis a vis Russia in the 1930s.ā Explain how your undergraduate training has prepared you to tackle this line of research.
Explain how your interests match both the strengths of the program to which you are applying and the research interests of specific faculty members.
A personal statement should not be a long document: 2-3 full pages tops.