I have several kids who get frustrated quickly. I suspect it's partly because a lot of things come easily to them, and they think that's the way it 'should' be. Over the years I've developed a large repertoire of things to say to help kids get past I'm no good at this! The quickest fix is simply to add a couple of key words:
"I'm no good at this!" ---> I'm no good at this yet.
"I can't do it!" ---> I can't do it unless I work hard.
"I'll never get this!" ---> I'll never get this if I don't stick with it.
It's all in the self-talk. There's a new study out that adds a dimension to self-talk that I haven't seen before. Apparently determination is fostered by questions more than by statements. People who declare "I will finish this project tonight!" don't follow through as well as people who ask themselves, "Will I finish this project tonight?" There's something about asking a Bob the Builder question (Can we build it? -- Yes we can!) that pushes one to respond in the affirmative, and builds motivation.
I'm pondering how to incorporate this into my parenting. Thus far I've rejected questions like, "Will it take a long time to pick up this enormous mess?", because I'm sure the response I get will be "Nooooooooo! I can't do that!"