Run on sentence........

Two or more independent clauses are joined with appropriate punctuation.

1) semi-colon if two alike independent clauses.

2) period

(http://grammar.ccc.commnet.edu/grammar/runons.htm)

Rule

Incorrect: I fell of my treadmill the wall didn't move so I hit it.

Correct: I fell off my treadmill; the wall didn't move, so I hit it.