2. how would your co-worker's laziness impact your performance and attitude?

If a co-worker is acting lazy and not doing their share of work, you may then feel the need to not do YOUR work. You may think, "why should I do my work if they're not doing theirs?"
Or, you may get angry at your co-worker and- depending on the job- you may work in an angry manner that can scare off customers.
However, this all depends on who you are as a person. If you let things like that get to you, or if you try to work harder to show your boss you mean business.

If the question is asking how YOU are impacted then answer how if will affect you in that situation.