Whenever Hannah decides she's not quite ready for bed, I try to find ways to stay quietly in her room. It assures her of my presence, but it doesn't disturb her getting to sleep. I'm also close by in case she does wake up so that I can calm her right back down. Most often I fold laundry, sort diapers, or start blogging on my phone. If I don't have my regular set of distractions, I take five or ten minutes to enjoy a few Sun Salutations. If you're familiar with yoga, these are the series of poses you do at the beginning of class for a warmup. After doing 4 or 5 vinyasas, I feel refreshed and calm. It doesn't stress me out if Hannah wakes back up and it's nice to be close to her while doing something great for myself.
Think about it, if your kids take 2 naps a day (or more) and then lay down for bed- that's 30 minutes of exercise right there. You should still do some exercise that gets your heart rate up, but this is a fantastic supplement. If you need a refresher on how to do a Sun Salutation check YouTube or this website.