|GMs, this is directed at you, but players need to read it too.
Do you see this? This is how your game should be.
Ask yourself if your game could possibly result in your characters riding giant tyrannosaurus zombies through busy city streets into the necromantic maelstrom of the birth of a new god of death. (Or something on the same scale of epic).
If not, look back on how the game has been going. Have you been too restrictive of your players? There is an urge that GMs get to work against the players, to prevent their game from being too easy and boring. Try and be aware of when you're doing this, and stop immediately. Better yet, ask your players to watch for this, and let you know right away.
This game is for them to shine, and live out some wish fulfillment. We're not talking about nerfing their enemies, or fudging dice rolls in their favor, we're talking about you being on their side, not against them. You want your players to not be afraid to do crazy, amazing things, at least once a "session".
Every time they do something mundane, ask yourself if there's a way you can turn it into crazy drama in a completely unexpected way. Ask yourself why they would want to do something mundane. Are they bored? Have they not gotten it through their heads that they are legends in the making, and legends don't do mundane? It could well be that their mundane action is something that they really don't care to look at more closely, but feel like its necessary. In that (rare) case I would let it go by, and make a note to avoid that kind of situation from then on.
My goal is to give them a sense of urgency, that time won't permit them to be boring, because the world is going to end if they don't pull out all the stops immediately. I want to reward them for pulling out the stops. I want them to say "That's so crazy, it just might work!" to each other, almost constantly.
To that end, throw out the rules whenever they're doing something cool. They're the stars, let them be stars. Don't pile "necessary" requirements on them, let them decide what will work and go with it. If it fails, it should fail in such an awesome way that no one is disappointed. Failures should build up to an even higher fever pitch of cool.