Have unconditional love to your children no matter what happens. Give them time even in the midst of this busy life - be one on one with them.
To keep children healty, it's important to keep them active. Of course you can control what goes into their mouths, but it's also about putting the active back into family activity. Go outside with them, live in the moment and encourage them. That'll help you find fulfillment in your life as well.
I realize the differences between my children and use what works for each of them individually.
From what I hear, it's a normal thing to feel guilty as a mother, especially when trying to fill the needs of a newborn along with maintaining what you had with your first child.