YOU SAID:

I am good at math, but sometimes like to not do it.

INTO JAPANESE

私は数学が得意ですが、数学をしたくないときもあります。

BACK INTO ENGLISH

I'm good at math, but sometimes I don't want to do math.

INTO JAPANESE

私は数学が得意ですが、時々数学をしたくないことがあります。

BACK INTO ENGLISH

I'm good at math, but sometimes I don't want to do math.