Hobbies throw haymakers at you when you don’t expect them.

Drumming, painting, rescuing bunnies — sheer joy in how good any of it can make you feel can be overwhelming. Hobbies aren’t jobs, but passionately, and positively, internalizing them as a calling can define our work, love, friendships and self-image.

An intensely sweet infusion of that rousing spirit transforms Whip It — Drew Barrymore’s directorial debut – from a quirky grrl-power movie about a women’s roller-derby team into one of 2009’s best films.

Like School of Rock, Whip It is a moving popular-movie meditation on the importance of seizing the now early, whatever that “now” might be. Twee and tough all at once, the film elbows aside sports-movie clichés with a thoughtful intelligence, an emphasis on self-reliance and all-too-rare cinematic portrayals of strong women.

Akin to Zombieland, Whip It uses its soundtrack for euphoric metaphors. Kings of Leon’s “Knocked Up” clashes with classical piano — perfect for the disconnection between Bliss Cavendar (Ellen Page) and a beauty pageant in which she’s entered.

Bliss is there by the will of her mother, Brooke (Marcia Gay Harden) — a former pageant champion who’s since taken to stress-smoking, a postal-service job and parenting around the timid approach of her husband, Earl (a long-lost Daniel Stern).

When a trio of women rolls into a clothing store, inspiration hits Bliss in the noggin. After going to a roller-derby match in Austin, Texas, Bliss’s baby-fatted wallflower sees an escape in a sport of self-assured, seriously fit women with wild stage names (Smashley Simpson, Rosa Sparks, Eva Destruction) and the Hurl Scouts squad.

“Put your skates on. Be your own hero,” says Hurl Scout Maggie Mayhem, played by Kristen Wiig, who — finally, finally, finally — offers a character, not brief comic relief. Once Bliss does — and becomes a Hurl Scouts star under the name Babe Ruthless — she discovers empowerment to blow by the borders of her small town.

Bliss picks up bruises, scrapes and wickedly toned muscles. Moreover, she begins to understand her own sexuality, the blue-sky spontaneity of the post-high school life and, eventually, an understanding for all the upheaval her parents have endured.

Drag Me To Hell was fine in its own genre, but it’s easy to see why Page ditched it for Whip It. No matter how mousy her characters might be, Page projects a proactive person waiting to break free – uncomfortable to merely react. It’s a snug fit for Bliss coming out of her shell and, in a lean year, perhaps worth another Oscar nod.

That said, Bliss isn’t without flaws. Barrymore and screenwriter Shauna Cross (adapting from her own novel) let relatable teenage contradictions and occasional pettiness carry the story. It’s not just through Bliss, but also through her friend Pash, thanks to the great comic timing of Alia Shawkat (Arrested Development).

They also understand no one should be judged by their best, or worst, moment, and let all characters run the spectrum. That includes Harden, in an atypically tender and tempered performance, and a playfully feral Juliette Lewis as Bliss’s rival, who has a compelling reason to envy attention lavished on Bliss.

The film is not without a romance for Bliss. But, as first flings go, Whip It understands connections aren’t necessarily commitments and that there’s a crucial distinction between what you’re infatuated with and what you love.

Also, Page, Harden and Stern share a great confrontational scene awash with harsh words and, later, simple apologies. That’s why they’re called ropes — sometimes you’ve got to be smashed against them to know what they protect you from.

No one expects Barrymore to be any sort of master filmmaker. But she has an atmospheric flair for the rowdy rink, growing pains and, not surprisingly, daffy comedy. Much of that comes from the Hurl Scouts’ couch, Razor (Andrew Wilson, better than Luke or Owen has been in some time) — for whom a disappointed curse word and guerrilla motivational tactics tend to work wonders.

From a technical perspective, she’s surrounded herself with seasoned collaborators (cinematographer Robert Yeoman, editor Dylan Tichenor). Together, they create a raucous rhythm to the roller-derby sequences, and the film is a triumph of location scouting, with Michigan standing in for Texas (save a few second-unit shots).

If there is any flaw, it’s the overuse of Jimmy Fallon as the obnoxious roller-derby announcer. His fast-tiring shtick is proof Fever Pitch might be the only thing in which he plays anything resembling a human being.

At least Fallon’s character gets one thing right, though, indirectly commenting on the totality of Whip It — you will enjoy the ever-loving shit out of it.