I have two kids - 4 and 6 - and even not being an at home mommy, it is a struggle to maintain the balance. My husband and I work at this as much as we work at all parts of our lives.
Some things that have worked for us:
Make a standing date night. We've identified a couple that lives nearby with kids about the same age as ours and on a sometimes weekly other times monthly basis, we trade babysitting. Having a deal with an outside couple means that they motivate us and we motivate them. Other friends have just found a sitter and set a standing weekly/biweekly date night. You have to do this because a healthy marriage is good for you and your kids. Maybe explain this to your husband and help him be in charge of date night - my husband seems to be the motivator on this front in our house. My girlfriend is the motivator in her household. Every household has one.
Take a class. It is incredibly reinvigorating to have time away from the kids, doing something just for you. And having a class on your schedule - something you've paid money for that doesn't wait for you - is motivating. You have to go, and you feel better when you do. If it weren't a recurring event on my calendar, I'd ultimately find an excuse not to go.
Throw family parties. We have dinner parties or park parties at least once a month. Sometimes we meet friends at a family friendly restaurant, other times they come over for a potluck, and if we can't muster either of those, we meet at the park with bagels and juice. The idea is to get the kids running around together watching each other so that we can sit and have adult conversation. If everyone pitches in, this is a lot easier than it sounds.
Go on a shopping spree. If only we all had a ton of expendable cash to spend on appearances, but even on a limited budget you need to once in a while clean out what you have and replace with an item or so that is fresh, up to date, and makes you feel sexy. Ask your husband or a girlfriend to watch the kids so that you can do this, but take a couple hours one day to update your wardrobe. If you feel good, you'll feel more like you.
Get dressed in the morning. I rarely wore makeup until I had kids. This is something I've added to my life as a way to make me feel more human. I just wear lipgloss, foundation, blush and mascara, but it makes me feel more alive. I also make a point of wearing cute clothes as opposed to comfortable clothes because, again, I'm getting dressed to make myself feel human. It just isn't the same if I've barely changed out of my night gown.
Buy some nice lingerie. If you're going to wear tshirts and jeans to soccer games and ballet - because they are most comfortable - at least wear sexy/cute underwear. Your husband will like it. You'll feel better...
Constantly reassess your balance. The number one conversation amongst my fellow moms is the work balance in the house. We often feel like we've got the most on our shoulders. In talking to my husband, the guys feel like the moms either don't want to go out (we're not as good at leaving the kids) or we don't give them dads a chance to be the nurturers/doctors/cooks/etc.
We've just gone through a reassessment in our household as despite the fact that we both have full time jobs, I'm the one making lunches, chauffeuring kids to soccer, gymnastics, leaving early to get them from after school programs, enforcing that homework get completed and extra work done where the kids need help, setting and taking time from work to attend doctor and dental appointments, making dinner, etc... I've been feeling overwhelmed. It just took a civil conversation explaining how I'm feeling and what I need help with (best if he volunteers :)). We've got more figuring out ahead, but the conversation helped.
I guess the bottom line is that it sounds like a lot of work, and truthfully, you have to constantly work at balancing you time into your life, but the things I've mentioned above are a lot easier than they sound. And for the impact - totally worth the energy.