Honestly some days I just don't know!!! I have a 4yo and a 20 month old ATM (as well as a 13yo DD) and it's still quite challenging. My 4yo will often make it hard to settle my toddler... I'll juuuuuust be lying my little one down in the cot and then BAM! in will walk my 4yo and say "I want to watch Thomas the tank Engine!!!" and my toddler will wake up and that's that. Gotta start all over again. Or one will be climbing the table while the other is ruining the carpet... what do I try to save? of course the toddler so there has been much more destruction since having more than 1 small child in the house. And then they will occassoinally fight. Oh the joy. This is why (one of many reasons) I waited 9 years to have another... and then another child. I think the reason it's hard though for me is because I have very little help with them. It's more the relentlessness than anything. Of course I love them both. Yes, I agree with 'capacity'. However I have also developed a long term illness which has reduced my capacity. So maybe my experience is worse than it would be if I was healthy.