at will

1. 任意; 随心所欲地

He told us that we could wander around at will.

他告诉我们说我们可以任意闲逛。

of one's own free will

1. 出于自愿

I did it of my own free will.

我是出于自愿做的。

with a will

1. 起劲地

They set to work with a will.

他们起劲地投入工作。

Where there's a will, there's a way.

1. 有志者事竟成。