1. 我必须开始做健身运动了。

[ wǒ bì xū kāi shǐ zuò jiàn shēn yùn dòng le 。 ]

I've got to start working out.

2. 你必须有自己的主见。

[ nǐ bì xū yǒu zì jǐ de zhǔ jiàn 。 ]

You should have a mind of your own.

3. 他们必须努力工作来支持他们的家。

[ tā mén bì xū nǔ lì gōng zuò lái zhī chí tā mén de jiā 。 ]

They have to work hard to support their family.

4. 我必须道歉!

[ wǒ bì xū dào qiàn ! ]

I must apologize!