For those of you that have dogs (specifically big dogs) how often do you walk them?

I feel awful, we haven't taken our 2 dogs out on a walk for probably 2 weeks.....we used to take them at least 3-4 times a week, or to the dog park. But getting further in my pregnancy, it's just not doable, I just ache all the time and walking sucks. DH has been so busy at work that he's just exhausted by the time he gets home.

Luckily we do have a fenced in back yard, and I will sit out there and throw the tennis ball for them for 30-45 minutes each night....but I feel like they still need to get out of the house/ guilt even hits with pets!