If you want to be more productive, hang out with productive people.
I would expect they'd only influence you about how they act at the time. If you hang out with someone who is usually productive, but at this moment is hanging out with a friend, it doesn't seem like it would help much.
Edit:
Also, this seems like a zero-sum game. You are less productive than people who are more productive than you, and they might not want that to rub off on them. Is there a good way to get around that?
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.