Credit: Jon Furniss/

Let the great slimdown begin!

Jessica Alba is ready to shed her baby weight. The Spy Kids 4 actress, 30, gave birth to her second child, daughter Haven Garner, on Aug. 13. And just over two weeks later, she went to back to the gym.

"I did my first day of workout since I had the baby," Alba Tweeted Aug. 30. "Just cardio for 40 minutes."

The svelte star explained that she got the A-OK from her physician. "My doc told me I could start after 2 wks," she wrote. "I'm going light, stationary bike and elliptical."

The second-time mom (she and husband Cash Warren also have daughter Honor, 3) offered advice to others on Twitter about post-baby diet, too. "I would keep your diet as healthy as possible 6 days a week and give yourself one day to indulge."

Other Alba-approved post-baby fitness tips? "Start with walking and throw in 3 sets of lunges 20 per leg. Your could do it while strolling your baby."

Before giving birth, she admitted to Lucky mag that she needs a little help curbing her appetite. "I have a hard time with portion control, so I have 1,200 calorie meals delivered," she said. "But I also work out, so basically I'm starving. It sucks. I drink a lot of water."