I think it is our role as adults to say -- out loud -- "yes it is fustrating to do it a 3rd time, or to pratice handwritting each day, but nothing is fun untill you are good at it, you do not want to be in high school and have you handwritting preventing you from doing wath you want" .... to make it 'real' and to -- put the reality of mastery and the need for it and the 'less than fuyn part of it' out tehre
I think it works better if you can create engaging and meaningful situations where your child experiences that doing something over and over again results in impressive long-term gains and a sense of self-satisfaction that comes through ease and improvement. I can tell my kids stuff like this until I'm blue in the face but they won't truly get it until they experience it for themselves. For us, outside music instrument lessons, vigorously but lovingly supported by parents at home, has been the best way to experience this. My 8-year-old has been playing violin for 5 years. When she meets challenges in math or handwriting she is likely to say something like "I need to practice this a few times every day to make it easy, just like with violin."