I don't know how old yours are. I only have one, who's about to turn 2 and just hitting that challenging stage.
I have days of shouting and exasperation. The running joke in the house is "God, it's like trying to reason with a one-year-old." Those are my selfish, self-pitying days, when all I want is to bury my face in a bucket of coffee and be allowed to read in bed quietly for just once in my life.
It is an effort, a really hard effort sometimes, but I try to defuse stroppy, grumpy situations with laughter.
If my daughter starts bleating or whining about something, I try - instead of getting pissed off - to pull a funny face and mimic her noise, but in a funny, theatrical, not derisive, way. It descends into a contest of who can make the stupidest noises and faces.
Or I say "Have you got grumps?" and get out the bicycle pump, which is for hunting grumps with, and I go pfft pfft pfft with it to chase the grumps out. Under her chin, under her armpits, etc. It sorts her out and makes her laugh 90% of the time.
Then I clap my hands and say "Right! Now we're going to do [xyz]", even if [xyz] is just getting some dried split peas and chucking them from one plastic cup to another, or putting the radio on and seeing who can dance the most ridiculously.
Really, it's about trying to enjoy the time rather than make it a struggle. I'd rather listen to my own sense of humour than my bad temper. But Jesus Christ it's tiring. And I only have one child, so I have no excuse to be tired really.