I have fallen fowl to doing this....
'The baby won't change our lives, he can fit in with us' - hahahahaha
'I won't be taking everything plus the kitchen sink away with us, he'll have to find other ways to entertain himself' - cue boot full to the brim to avoid boredom whingeing
I use to think pregnant women used to milk being ill, until I was pregnant myself and realised how awful it can be.
Birth plan, no pain relief, water birth etc etc. Real life, gas & air, epidural, forceps, stirrups.
I won?t lose my temper, I?ll just sit down and rationally talk to my DS about whatever it is he?s upset about 
I used to only but organic free range meat, until I discovered nursery fees cost the same (at first even more) than our rent.
I used to think grimace at screaming toddlers going into meltdown on the bus, now it's me when my DS decides he wants off the bus, NOW!
We live and learn.