“Look, if you just let your arm drop by effect of gravity, you send the fly ten meters away effortlessly and accurately.”

That is my way of showing how easy it is to make a pick up and lay down cast—elbow forward style— at the most usual trout fishing distances. However, something comes to my mind in those instances, something that I never say to my student:
“If it is so easy, why did it take me so much time, effort and frustration to do it properly?”