How much emotion do you put on the web?

I’ve been doing some thinking about my personal interactions, both online and off. I’m not a private person by nature, I tend to share quite a bit if asked.

On the other hand, I do a fair bit of self censoring on the web. In particular, I try to present myself as unwaveringly optimistic (which isn’t so bad, I’m optimistic by nature). However, that does make my online-self idealized. 

How do you strike a balance? What’s the value in being ‘real’ vs. being positive? How do you balance your personal brand while balancing the value of authenticity? Where do you draw the line?