There are three lines you braid together to create a compelling plot. One is conflict, one is motivation, and the third is escalation.
Conflict: somebody wants something, and someone or something stands in their way.
Motivation: why do they want it?
Escalation: This is where you make your characters work to get what they want, and make them face just how far they will go to get it.
There's a great analogy about putting your character up a tree, and then throwing rocks at them. That's exactly how you need to think of escalation. The stakes have get to get higher and your protagonist has got to walk through the flames of Hell to reach their goal. Okay, maybe not literally, unless you're writing a paranormal and your protagonist does in fact walk through the flames of Hell. ;) The point is, you have to make it harder and harder for your protagonist to reach their goal. You have to torture them, you have to ratchet up the tension and the stakes higher and higher until your protagonist is standing on the edge of a cliff, staring into an abyss and thinking all is lost. And then you have to push them off the cliff.
I know you don't want to. Believe me, it's something I struggle with. I love my characters and I want them all to be happy and spending their days doing whatever they think of as fun. In Mojo Queen, I would have been very happy to have Daniel float through the book with a drink in one hand, always on the verge of bursting into song. (A really cheesy off-key rendition of some classic country song, maybe in a small town bar on karaoke night - like this song perhaps.) But that would have been too easy and it would have lacked the tension needed to escalate the plot. So I had to be mean to Daniel. I had to torture him. There were snakes. *shudder* But when it was over I was really proud of myself for having had the fortitude to put such a beloved character through something like that. Writing is the only place where its acceptable to hurt the ones you love. You may love your characters, but you can't just hand them a happy ending on a silver platter. For the sake of the story, they have to work for it. They have to struggle and sweat and take their lumps and have all manner of obstacles put in their way. It has to be this way because in the end it makes the payoff - the characters getting what they want - all the sweeter.
My recipe for escalation is pretty simple: Out of the frying pan, into the fire. Lather, rinse, repeat. When everything seems darkest, push them off a cliff and let them fly into Thunderdome. With a strong enough motivation leading their actions it will make perfect sense for the character to wind up there. After all, they've come this far, been through the worst the world could throw at them, and clearly they want to achieve their goal bad enough that they haven't called it quits and gone home. The stakes are high and they are in it to win it. Once you've put them through a gauntlet, you can let them.