Super model Adriana Lima after training in Miami on October 7, 2012. Credit: BAUER-GRIFFIN.COM

New mom Adriana Lima is working hard to get her pre-baby body back!

With her return to the Victoria's Secret Fashion Show runway just two months away, the 31-year-old is anxious to slim down before she dons those famous angel wings.

On Sunday, Lima -- who welcomed daughter Sienna on September 12 -- worked up a sweat during a workout in Miami Beach. "Just finish workout," she tweeted midway through her session, along with an image of the sweaty model hard at work.

Lima's return to the gym comes mere weeks after she and husband Marko Jaric celebrated Sienna's birth. "Marko and I are overjoyed to welcome Sienna into our family, and Valentina is looking forward to becoming a big sister," the model shared in a statement about Sienna, who was born at 1 p.m. and weighed in at approximately 7 pounds on arrival.

The model and her NBA star husband's older daughter, Valentina, was born in 2009 -- the same year they tied the knot. "My favorite job in the world is being a mom! My family could not be more happy," the model tweeted when confirming she was expecting Sienna in March.

As she and Jaric celebrate their newborn, the model mom tells Us Weekly big sis Valentina, 2, is already growing up fast. "She knows already how to count to five," Lima gushed to Us. "And she knows colors, like red, pink, white -- it's so cute! Everyday it's something new."

Lima will join Victoria's Secret's other angels for the annual fashion show airing December 4 on CBS.