Imposing self limits...

[Spidey44]

So I'm new to online poker... Do you all give your self a limit when you play? What I mean by this, as an example, if I play some low limit tables, I'll sit down with X bucks, and I was thinking if I lose X in that session, it's time to get up. On the flip side, if I am up by half of what I sit down with, I should get up. Am I limiting myself or do you think this is a smart way to play?

Thanks!