When did you get back to workouts after pregnancy?

Here's the deal...before I got pregnant I was working out a lot...doing triathlons and in great shape...I have always worked out. I told myself I would continue to do so throughout my pregnancy and did not (couldn't stay awake for the first trimester...in school...moved). I had my baby in November-she was 6 weeks early. I have been so tired and have little help with her...I feel terrible for not already working out regularly and am starting to lose faith in my ability to lose this weight! I just want to hear from someone who has been through this and how it worked out for you. I have never been in such bad shape and had no idea what having a baby does to your body!