Check out this article in the Daily Herald today with a simple 15-minute circuit with minimal equipment.
Sometimes even 5 minutes is better than no exercise.  For example, this morning I ran around the block, which is an 800, in approximately 6 minutes. Following up with a double-duty stretch completed my morning workout on a busy workday. 
Start with the slant board stretch, one leg at a time.  Lean against the wall with one hand, then take your opposite foot and do a quad stretch with the one leg while stretching the calf with the other. The following two videos from YouTube show each stretch separately; simply put them together when you feel ready.

As a nursing mom, do you worry that by feeding your baby you are losing too much calcium from your own bones? Surprisingly, recent studies have shown that despite a temporary loss of bone density during breastfeeding, mothers quickly gain back the bone they lost (within three years).  Even better, a Finnish study found that long-term breastfeeding - a total of 33 months over a lifetime - led not just to stronger bones, but bigger bones later in life. 

Another study showed that during the regain of bone post nursing, the mother's bones were actually remodeled with new bone.  Any microscopic fissures were replaced with smooth, strong bone. 

Of course, mothers are advised to eat calcium rich foods during pregnancy and nursing along with a healthy balanced diet.

But it turns out that breastfeeding is healthy not just for baby, but for mom, too.