I was determined to be your hero

be determined to 是坚定；坚决；决心的意思 是固定短语 不是表示被动语态 所以原句是对的
可以看以下例句：
1. I\'m determined to leave.
我决意要走了。
来源： dj.iciba.com
2. They were determined to face up to the difficulties.
他们决心面对这些困难。
来源： dj.iciba.com
3. They were determined to fight on to the end.
他们决心斗争到底。
来源： dj.iciba.com
4. He is determined to go to Africa on his own
他决定一个人去非洲。
来源： dj.iciba.com
5. The government is determined to put an end to terrorism
政府决心遏止恐怖主义活动
来源： dj.iciba.com
6. We are determined to face out the situation.
我们决心勇敢地面对这种局面。
来源： dj.iciba.com
7. We are determined to put through our project.
我们决心完成我们的计划。
来源： dj.iciba.com
8. He seemed determined to pick a quarrel with us.
他似乎存心要找我们吵架。
来源： dj.iciba.com
9. something determined in relation to something that includes it
与其包含在内的事物相关
来源： dj.iciba.com
10. George wa