You should say:
what the sport is
how you know about it
is it difficult
and explain why you think it is exciting.
I think the most popular sport in China is table tennis. It doesn't require intensive facility but only a pair of bats, a table tennis ball and a table, and doesn’t matter what the weather is, and is also easy to learn. You can find people at different ages playing it in the community, even some old people.
Actually, there are several physical benefits of playing table tennis, like your reflexes and hand-eye coordination would become quicker and more refined. And the most important is that it can build your body strength. Though I can’t play it, I often watch table tennis games.
Table tennis is our national ball, and our players have won so many prizes with their excellent skills. Their games always make us excited, and we are proud of them. I enjoy watching the games, and perhaps I’ll learn how to play it soon. In a word, this is a sport with a lot of fun. That’s why I think table tennis is an exciting sport.