在英语中，想要表达“我由我决定”这样的自我主张，有几种不同的方式可以做到既地道又符合语境。以下是一些表达方法和相应的使用场景：
1. “I decide for myself”
这是一种非常直接且常见的表达方式。简单明了，适合在各种正式或非正式场合使用。
例句：
- “I decide for myself what’s best for me, and no one else can tell me what to do.”
- “It’s important to me that I decide for myself where I want to go to college.”
2. “I make my own decisions”
这种表达更加正式一些，通常用于强调个人的独立性。
例句：
- “I make my own decisions, and I’m proud of the choices I’ve made so far.”
- “I value the autonomy to make my own decisions, rather than following others.”
3. “I choose to decide on my own”
这种说法稍微有点文艺气息，适合在书面语或者较为正式的交流中使用。
例句：
- “I choose to decide on my own, without any external influence.”
- “I believe in the power of self-determination, so I choose to decide on my own path.”
4. “It’s my decision to make”
这种表达方式强调了决定的主权完全属于说话者。
例句：
- “It’s my decision to make, and I will not let others sway me.”
- “Ultimately, it’s my decision to make, and I stand by my choice.”
5. “I’m in charge of my own decisions”
这种说法更加口语化，适合在日常对话中使用。
例句：
- “I’m in charge of my own decisions, and I won’t let anyone tell me what to do.”
- “I take full responsibility for my decisions, and I make them independently.”
在使用这些表达时，根据不同的语境和目的，你可能需要调整语气的强弱、正式程度以及句子的结构。记住，英语中的表达往往不仅仅是字面的意思，还包括说话者的情感和态度。