I have been meeting with lots of parents recently to discuss their parenting challenges. The converstaion always comes aorund to some simple techniques they can use to help their children deal with frustration. When my child was 3, I made up and taught her these simple steps:
1 deep breath
2 feet walking
3 cool thoughts
As a child therapist trained in cognitive behavioral therapy, I wanted to teach her some techniques to begin learning to regulate her emotions but also make them easy for her to remember. I taught her when she was calm and we practiced. First, she would take one deep breath. Second, she would use her two feet to walk away from the situation that was frustrating her. Third, she would think 3 cool thoughts. Cool thoughts are thoughts that help you calm down. An example of a cool thought for a child is "when my cousin takes my toy, I can ask an adult for help." An example of a cool thought for an adult is "If I take a quick walk I can come back to this frustrating task with fresh eyes." Thinking cool thoughts takes some practice, but even small children can get the hang of it.
One of the best things about it was that I could remind or "cue" her without saying a word. It was a like a secret signal we had. If I saw her getting frustrated, I would smile in encouragement and hold up one, two, then three fingers. It was a way I could remind her without embarrassing her.
So try it with your kids, and try it yourself. I can speak from personal experience, it works for both!