Exercise!

So I am 14 weeks as of today. Which is, according to some, the start of the second trimester. According to others, that was last week. I started exercise again today (I haven't been really exercising since I found out I was pregnant. Just walking) and holy cow, have I gotten out of shape in 10 weeks! I was in really good shape before pregnancy, because I was training for Tough Mudder, now I'm out of breath before the warm-ups are over, and my belly hurts quickly. :P I am going to have to start doing my pregnancy yoga every day so that I can stay in shape without killing myself lol. Does anyone have any recommendations for exercise that is easier on a pregnant body?