A "Run-On" Sentence

A "run-on" sentence: Two sentences that have no conjunction between them that are put together as one sentence either with a comma instead of a period or with no punctuation
at all.

...He always came in late and sat down and checked Facebook before he even started to
do any work, that's right.
...She owned a condo, he owned a house.
...The door was open I walked right in.

A long sentence with lots of clauses is not a run-on unless it has one of the two conditions listed above.

...We said that we would gather around 5:00 and that we would discuss the situation and
that we would try to reach some kind of conclusion about the situation that we were
facing and that we would all agree to abide by the group decision and put aside our own differences and feelings about the situation and that we would support the group decision going forward and that we would not mention again the problems we have had with it.

Happy punctuating!