I find it so difficult, I have 3 kids 11 9 and 5 and my dss 11 is not mine.
I think it's harder when they are your own as your time is not your own, things usually don't go to plan and also you need to remember that most kids behave differently in nursery settings.
You wouldn't believe the contrast that I experienced with my dd when she was at nursery, butter wouldn't melt! But when she was home she was a little rascal!
As a mother with a young one you've likely had minimal sleep for god knows how long and therefor you're knackered most of the time and even the simplest of jobs and playing with little ones becomes similar to climbing a mountain.... not only this, one bad night sleep leads to one lazy day and then things start to build up massively.
I think lack of sleep is the main issue with parents of little ones... now my kids are older I am coping better but their arguing and bickering, wants and demands are practically endless... that's fine, I expect it, but it doesn't mean it's not tough! I still have to factor in time for myself and chores. To get back on top I have started expecting my older kids and even the 5 year old to help me. They hoover for me, my 5yo puts washing in the machine for me and carries the dry lot upstairs and actually they like to help.
I don't see how someone who works in childcare where all their time is dedicated to engaging the child and likely working in a team of other equally well rested women and men, who doesn't have kids of their own (so has slept well for as long as they can remember), and gets paid for it, can criticise a parent who is moaning about finding it tough
Moaning about it is a good way to vent as there's no getting out of it, and a good way to relate to others going through the same thing.
Having kids is a choice but you never know how your kids are going to turn out and behave.