Hi now that I am 17 weeks I want to start exercising. I have started walking 15~20 mins and slowing am thinking of increasing the time. though I am not able to walk fast, it is more like a stroll. I also want to start yoga and am thinking of getting a book. Before pregnancy I used to walk a lot and fast and I used to do yoga but that was off and on. Do you have any suggestions, please do let me know.