On Giving and Not Getting

Do you give more than you get back?  Does it make sense to keep giving when it is unrequited?

You hear this most often in reference to love, but I'm thinking in other contexts too.

Are you the polite type that always says please and thank you? Opens doors for people? Gives up your seat on the bus? 

If that is never, ever, ever reciprocated do you keep doing it because you feel it's right? Or do you eventually become embittered?

I know for me there are things I like to do that I wish the recipients would reciprocate or at least acknowledge...but on the other hand, they're things I enjoy doing...so I'm thinking I should just take pleasure in that and leave it be. :)

What do you think? I'm curious.

Another random thought...does anyone else have the issue with their brain and mouth being completely disconnected? Sometimes I find people will say, "Have a nice day" or "Thanks for coming" and I think, "Thanks, you too" or "Thank you for having us" but it totally fails to exit my mouth and by the time I realize I didn't actually say anything, it's too late and I look like a jerk.