意志是可以用WILL来表达的，WILL表意志与意愿.如：钢铁意志：will of steel.
有志者事竟成：Where there is a will, there is a way.

作文：
My Will
The will is the psychological process that poeple control their action voluntarily and get over the difficulties for some purpose. I don't know if I am tough-minded or weak-willed.But if the full mark is 10, my self-conscious would be 5,steadiness gets 8,decision gets 5 and self-mastery gets 7.
I believe that where there is a will,there is a way,so I am trying to be strong-minded.

我的意志

意志是人为了一定的目的，自觉地组织自己的行为，并克服困难的心理过程。我不知道我的意志是强还是弱。如果用10分为满分，我的自觉性大约5分，坚定性8分，果断性5分，自制力7分。
我相信有志者，事竞成，所以我要做一个意志坚强的人。 高考试卷