Taking time for yourself is completely fine and there is no need to feel guilty about drawing yourself a bubble bath, lighting some candles and declaring that there is to be no mom, mommy, mama, mom at the door. You need that time and space to recharge your batteries!
If you're finding it difficult to work self care into your daily routine, set a goal of once a week. Once a week, take yourself for a coffee. Go after the kiddos are in bed (hello, decaf!) and tell your spouse that you just need one evening a week to yourself. You'll be surprised how much better and calmer you feel when you get out of the house once a week.
Exercise! Yes, I know it's probably the last thing that you want to do, but I can speak from experience on this one. Getting outside for a run, or challenging yourself to some indoor strength training while the baby is napping...it releases all of the happy endorphins and you'll feel really great about what you have physically accomplished once you are done.
When was the last time that you went on a date with your spouse? I bet it involved a baby in the carseat under the table, or being worn on your chest. That's not a date, and you know it! Call in the reinforcements and go out for dinner. Can't take that much time away? Make it a drink, or share a dessert.
Find something that is uniquely yours and hold on for dear life. When I was 5 months postpartum with my first and knee deep in postpartum depression, I started painting again, and I didn't look back. My studio is my space to breathe, and I am so thankful to have it. It helps me be centred and it's a place that is just mine. My son knows that he's not allowed in there unless I invite him in, and having that control helps me stay even.
The point of self care is to take time out, just for yourself. To breathe, give yourself space and realize that you are more than just a mom. You are still a person, with thoughts, ideals, interests and passions. Don't lose sight of that due to late night feedings, crying babies and toddlers who ask a million (and one) questions.
Be you and take care of yourself!