Correcting Run-On Sentences. 1  Use a period. 2  The easiest way to fix a run-on is to split the sentence into smaller sentences using a period. 3  Example: I love to write papers.4  I would write one every day if I had the time. 5  Use a semicolon. Use a period. 2  The easiest way to fix a run-on is to split the sentence into smaller sentences using a period. 3  Example: I love to write papers. 4  I would write one every day if I had the time. 5  Use a semicolon.