The `Spy Kids 4` actress has begun a keep-fit regime in order to get her pre-pregnancy figure back, just two weeks after giving birth to second daughter Haven. She tweeted: "I did my first day of wrkout since I had the baby, just cardio for 40 min. -it`s a start. Anyone else starting a fitness regimen?(sic) "my doc told me I could start after 2 wks. -im going light, stationary bike and elliptical" Responding to tweets about returning to exercise from fans, she added: "start with walking and throw in 3 sets of lunges 20 per leg. U could do it while strolling ur baby. commit to 10 min a day for a wk then add another 10 until u get up 2 40 min a day. It`s easier to ease into it.(sic)" Jessica also revealed she doesn`t stick to a healthy eating plan all of the time, allowing herself to indulge in her favourite calorific treats once a week. She wrote: "i would keep ur diet as healthy as possible 6 days a wk and give urself 1 day to indulge.(sic)" Before giving birth to Haven, Jessica - who also has three-year-old daughter Honor with husband Cash Warren - admitted she had been planning her workouts to get back in shape after giving birth, even though she hates exercising. She said: "Working out every day for even just 45 minutes is good for my mental state. "Getting dressed and actually doing it is the worst. It`s hard to get motivated. "In the gym, I have, like, five things to distract me: TV, iPod, magazines. "Working partners are good, too, so you can chat and not just drown in your own misery. Sorry, does that sound bad? I just hate working out."