(as) tough as old boots idiom UK
十分强壮；非常坚强
very strong, and not easily made weaker
He might be in his eighties but he's tough as old boots, that man. 那个男人可能已经有80多岁了，可他身体依然硬朗。
informal (US also (as) tough as shoe leather)（食物）非常老，很难切，嚼不动
Tough food is very difficult to cut or eat.