As fit as a fiddle.

体壮无比。

My grandmother's 89, but she's as fit as a fiddle.

我祖母已经89岁了，但身体仍很健康。

Gordon: I am as fit as a fiddle, and as happy as a kid in a candy store.

戈登：我精神抖擞，而且高兴得象一个进了糖果店的小孩子。