Another trick you can use to force your characters to remain active instead of passive is to put them through hell.
And now I will use an example from my favorite of all favorite shows...
MAKE IT OR BREAK IT!
That's right! And you forgot all about it...
So if you remember from last time I discussed the awesomeness that is the show (BTW, I'm now making Twin watch it with me. Converting the unsuspecting, one person at a time...) Payson broke her back in the season finale last season and her doctors said she wouldn't ever do gymnastics again. Which sucks for her because she was a favorite for the 2012 Olympics.
So Payson tries to pretend it doesn't bother her, but of course it does and she alienates her friends and family and breaks all her trophies and refuses to even go to The Rock to visit the other gymnasts or consider being a gymnastics coach.
So things are crappy for Payson.
Then, her pseudo boyfriend tells her about this back surgeon in LA who is the best in the world. So even though Payson and her parents decided she wouldn't see any more doctors, Payson gets her hopes up about this doctor and convinces her mom to allow her to get a consult.
The new super doctor tells her that he agrees with her original prognosis. No more gymnastics.
So Payson is broken hearted again.
Payson then has to go to public school, because there's no point to being home schooled anymore. She hangs out with a bit of a bad crowd and gets in trouble based purely on association, but this helps her realize that she can't spend her whole life thinking about how she can no longer be a gymnast. She has to move on, and find something else she'll love just as much.
So things are looking up for Payson, she's making new friends, joining clubs at school, gets to go to Prom and doesn't even have to wear her back brace at the dance.
And then, a doctor from Europe calls Payson's father and advises them that she believes she can perform an experimental surgery which will allow Payson to compete in gymnastics again.
Payson is excited about the chance, but she catches her parents fighting over the idea and because she doesn't want to be the source of their arguments or their fear she tells them she doesn't want the surgery.
If we look over all of these scenes (which of course have happened over the span of 8 or so episodes) we can see that every and any time Payson starts to feel good, or happy or things start to "come up Milhouse" for her, things then go to crap.
If you continue to throw horrible things at your characters, drag them through hell, then it's difficult for them to remain passive.
But you want to be careful that you allow the characters to make a mess of things as much as possible. Yes, the doctor calling from Europe is a bit of Deus Ex Machina (I LOVE saying that), BUT it's going to come down to Payson deciding if she wants to take the risk of surgery (a surgery that could possibly leave her paralyzed) in order to get another chance at her lifelong dream.
If your characters try and fix the bad things that happen to them, make their solutions cause even more problems (for example, Payson's big let down at the LA surgeon's is due purely because she fully believed she would be fixed and convinced her mom to bring her to LA for the consult. She caused herself that moment of heartbreak).
So, in recap, ways to avoid passivity = bad things happen to MC, MC tries to fix bad thing, which makes things worse, which MC tries to fix, which makes things worse, etc, until we reach the end and (hopefully) a point of change for the character.
You want to be careful that you have moments of breathing space for your readers, give a little taste of good things before the next disaster happens. This will allow your reader to take a breath and will also make the next disaster even weightier if things were going OK for a bit.
Again these are all things I try to keep in mind as I'm drafting, but truthfully I'll have to go back in during revisions to heighten the drama in each scene.
Does anyone else follow the "drag your MC through hell" approach to prevent them from remaining passive?