"Extensive research has established a substantial link between mothers who feel depressed and “negative outcomes” in their children, such as acting out and other behavior problems. Parental depression actually seems to cause behavioral problems in kids; it also makes our parenting less effective."
Children need about 10 hours of sleep per night. Very young children also benefit from naps during the day. Make bedtime special with a routine that includes bathing, teeth brushing, getting ready for bed, and reading a story in bed. Choose relaxing or happy stories... stay away from scary stories just before bed (these can cause nightmares).
Promote good personal habits
Make sure children always wash hands after using the restroom, before eating, before helping with food, and after wiping their nose. Teach them how to blow their nose into a tissue. Teach them to cough into the crook of their elbow instead of out into the open air. These measures may do more to protect those around them than protect themselves...but maybe their good habits will spread to their peers.
Involve them in food decision choices (e.g. Why we're having that for dinner). Show them a food chart and the benefits of healthy eating.
Remind them why exercise is so important and all the benefits they will gain (better fitness, improved strength).
Keep Stress Low
Take time to talk with your child every day so that they feel comfortable letting you know what's on their mind. Stress can cause physical illness.