What exercise can be done shortly after a hysterectomy?

I recently had a hysterectomy and now, 3 weeks later, find out that i over did it. duh, i am a single mom, full time college student. I was in decent shape before the surgery, now i am mush. I am 5'9", before the surgery I weighed 144# and liked it, now I am 130# and can not stand to feel my body jiggle nor just feel like I have NO ENERGY. I asked the doctor what I could do to get back in shape and she said that I was not understanding her when she said to 'lay low'. I don't want to feel this way, there has got to be something that I can do.