A few things that I do:
1 - I make certain to get to church every Sunday. It fills my soul, the kids have fun in Sunday School and I have an hour and a half I'm not chasing them.
2 - CBS - Community Bible Study. It's FABULOUS! Their kids program is FABULOUS and the kids are happy, well taken care of and have a wonderful time learning about Christ while you get to do a Bible Study and have fellowship with other women, a lot of whom are also Moms.
3 - make sure to get away for at least an hour by yourself at least every weekend. Go to Starbucks or some place, sit down, have a cup of coffee or tea, read a magazine or book or whatever. Just take an hour to yourself where you don't have to be "on". It is my sanity - particularly when DH has been out of town all week.
4 - schedule time with friends at least once a month and make sure that time doesn't include ANY kids. There is plenty of time to get together for play dates or whatever, but make sure you make time for yourself with friends, too. A few of my girl friends and I meet for breakfast once per month for about 3 hrs.
5 - don't sweat the small stuff. I used to stress about the house being unkempt when people stopped by during the day. The fact is, there will be folded laundry on my couch mid day pretty much every day, there will be toys strewn all over the house when my kids (15 mo and 3 yrs) are awake and if its in the afternoon, there will probably be pots, pans and dishes in the sink. It won't always be that way, but with a young toddler and a preschooler, I rarely get to finish a project (even just laundry) before he's trying to climb into the dog bowl, gouge his eye out with the toy hammer, eat his sister's crayons, climb on the dining room chair, climb on the back of the couch, etc...
6 - meals. I feed my family well, but no one every died from the occassional batch of fish sticks, chicken nuggets or tater tots. Give yourself latitude to do what you need to do sometimes.
My biggest piece of advice - activities for the kids. Do only as much as YOU want to do, YOU can afford and YOU can stay sane with. I like the kids to have something outside the house to do every day, partly so I get out of the house and around other adults. Check out library story time, indoor play parks during the winter, Gymboree or Socccer Tots or Kindermusik. Just find some things for you guys to do together so you get to be around other adults and have fun with yoru kids. I start to get depressed when I'm sitting in the house day after day isolated. So we just make sure to get out. When its not raining we make sure to go to the park.
Sorry for the novel... LOL.
"Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment." (Matthew 22:37-38)