I try extra outdoor time on rough days, or a nice long walk, as it's good for my mental health, as well as calming the kids. I make my 2 year olds walk(no stroller) so sometimes our walks are a full hour long. It also improves nap times for the day. Also, have a stash of unique new toys or crafts handy to pull out, as they always enjoy something new. We all have those days!