I like this post from @devilgate about not being discouraged to write, even when we know that doing more than writing could have a better impact:

But not everyone can do more, or give more. And even those who can, or could or should: for some of us, writing is not just what we do, it’s what we are. We need to write.

With politics there’s also an opposite problem, avoiding blogging about something just because it’s a controversial topic. The web is a big place with room to explore a lot of ideas, we probably shouldn’t second-guess ourselves as much as we sometimes do.