It's very hard work. I set up my first business whilst still working full time, then I left work to concentrate on it full time, got pregnant with DH and the business went from strength to strength. Cue DC2, I've just sold first business as a going concern for lump sum and as a glutton for punishment, set up business 2 whilst looking after a toddler and a baby.
That's now taking off and was my dream business I aspired to do 5 years ago. I look after them all day, DC1 will be starting nursery in January, I have no family nearby and DC2 is teething waking up 5-11 times a night. But I love it, it's keeping my mind active. I do get frustrated that I can't do more some days, but I'm doing enough.