给出一篇文章，将其中的动词转换为其相应的名词形式，并输出结果。


Although John prefers skiing to any other outdoor activity, he has never participated in a skiing competition. Last winter, he finally achieved his lifelong goal and participated in the national skiing championship.
Although John prefers skiing to any other outdoor activity, he has never participated in a skiing competition. Last winter, he finally achieved his lifelong goal and participated in the national skiing championship.

Naming the difference that ski is to the preferred outdoor activities of John, yet he had yet to participate in a skiing competition. During the last winter, he ultimately attained his lifelong goal and joined the national skiing championship.