Amanda Schwab/AP

& Jessica Simpson poses on the red carpet at New York's Museum of Modern Art on Nov. 29, 2011.

Jessica Simpson is eager to start work on her next business venture: losing weight.

The new mom, who gave birth to daughter Maxwell Drew on May 1, is set to make $4 million from a deal she recently signed with Weight Watchers, according to Us Weekly.

"As soon as Jessica heals from the C-section, she is extremely determined to get back in the gym and work out," a source told the magazine. "She wants to show the world and is excited to do it."

The pressure is now on for Simpson, whose weight gain was scrutinized towards the end of her pregnancy. The 5-foot-3 star admitted to weighing 170 pounds when she posed nude in January at just five-months pregnant for the April cover of Elle.

However, despite the public attention surrounding her burgeoning belly, Simpson admitted to enjoying her time away from counting calories.

"I had a great pregnancy. Eating and not having to worry too much about it has been fun," she told Hello! magazine in March. "Taking a break from working out has definitely been fun. But I'm ready for it to be over. I'm ready to have my body back!"

Now that she and fiancé Eric Johnson have welcomed their first child, Simpson has her work cut out for her.

"She'll have to meet the weight-loss goals for the deal to go through," the source told Us. "She hasn't chosen a trainer yet. In fact, she hasn't even thought about working out for a year. But if she wants this, she'll need to work out a good five times a week."

In addition to the lucrative weight loss deal, Simpson has also sold the first photos of baby Maxwell to People magazine for $800,000, Women's Wear Daily reported. The star's bank account will also likely get a bump after the launch of her upcoming line of apparel for Destination Maternity.