Answer by Professional Japanese Teacher
Miki chan nara dekiruyo.
You can do it, Miki.
Kenta kun nara dekiruyo.
You can do it, Kenta.
“できる dekiru” means “can do”. “なら nara” is attached to nouns like “あなたなら anata nara”, “きみなら kimi nara” and it means “if we are talking about ~”. When speaking to young children, it would be good to call them by their names directly. Use “～ちゃん ~chan” for girls and “～くん ~kun” for boys to show your love for them. You can also use “chan” for boys. Adding a “よ yo” at the end of the sentence conveys your encouragement to the children. English-speaking gyms are popular in Japan! I think the children will understand you if you praise them in English, but I also understand how you wish to convey an important message to them in their language. Speaking in Japanese to children who are nervous will surely soothe their nerves.