‘Crazy’ NYC Marathon fanatics are as rabid as the runners, but at least they have mimosas and bagels

For Brooklynite Lauren Rutkowski, 34, the day of the TCS New York City Marathon is perhaps the most important on the calendar — one she starts early in the morning, carb-loading on bagels near her home in Cobble Hill before hopping the subway to where the action is.

But the marketing manager won’t be running the five-borough race.

Instead, she’s one of 2 million New Yorkers and out-of-town spectators expected to show up bright and early this Sunday to cheer on a record-breaking 55,000 runners from all over the world, shouting encouragement from behind police barricades.

It’s an experience, Rutkowski, whose favorite viewing spot is near Central Park, said she wouldn’t miss for the world — one of the few times each year when New Yorkers put their differences aside and come together for a common goal.

“There’s something so wonderful and community-based about marathon day. Everyone is happy for everyone else, and you see all of the best parts of New York,” the superfan told The Post.

And runners aren’t the only ones training all year for the big day — there’s an art to watching, too. That includes day-of rituals followed by people like Rachel Naurath, 33, who wakes up at 6:30 a.m. on marathon day morning to pop across the shuttered intersection of Fourth Avenue and Baltic Street to grab a coffee — and “post up with enough time to catch the first waves,” she told The Post.