Just started reading, don't know if this point was made yet.
We are mostly (or all here) a bunch of youngsters, which barely reached the 30s or 40s, and we are complaining for things that last exactly 10-13 years at most. Once you reach that stage you have biggies to help, and to watch the children etc...
We should all remember that there is a long life from the 45 till the 120, and even longer from 120 and on. Ask anybody that finished (or in middle of) marrying off his children, if he regrets one second bringing down so many children with all those years he suffered. I guarantee you won't find a single negative response. The people that have a lot of children enjoy every minute of family joy and growth throughout the years to come.
Of course, we should also take into consideration the general Jewish concept that all mitzvis and maasim tovim that children and grand children do all years to come are to the benefit of the father/grandfather that brought them down to this world.
So basically, it pays to suffer a bit for a few years, knowing that for many years while living on this earth, and lnetzech netzachim, you'd be grateful and thankful to yourself for all those efforts.
And don't forget, that even in those years, you still have joy and nachas from all the good moments (which are sometimes the majority, but you forget after one bad night).
I would wish if anybody above 40 or 50 with a lot of children can chime in to agree or disagree with what said.