You need to be on your toes almost all of the time. Children have no real capacity to think ahead, no capacity to be on the lookout for the unexpected. They need very watchful grown-ups to do this kind of thinking for them. And the job can be exhausting. Young children also need so much help.
Every parent feels pecked at.
That is one way of saying that young children live in a different world from ours. They behave in different ways. They ask a million questions. They poke into places that are none of their business. They often leave a mess behind, wherever they go.