The whole "does it make my life happier" is such a shallow consumer thing.
When I was younger I led an interesting life in many ways but I have never had the intensity of experience I have with and about my children. Another really surprising thing was finding out how much I connect back with society - I want to be part of society and change it and make it better - I get what it is for.
Children are not a lifestyle accessory and as the poster above says they push you into all sorts of aspects of your self in all sorts of interesting ways.
The mixture of a startup and three small children has certainly been entertaining and there have been times when I am so exhausted I have nothing else to give but then to go and do something simple - like bathing the children or doing something in the garden with them and it makes it all worth while.
As I frequently find myself telling my children: Things in life that aren't challenging aren't worth while (possibly hyperbole but you get my point)