I don't know why you insist on talking about it.

我不知道你为什么坚持要讨论此事

I insist on doing more work.

我坚持要做更多工作。

We insist on doing it in our own way.

我们坚持按自己的方法做。

If you insist on doing something, do it everyday.

如果你希望坚持做某件事，那就坚持每天做。

If you insist on doing so, then we have to work overtime.

如果你坚持要这么做，那么我们只好加班了。

If you insist on doing it, you are doing a foolish thing.

如果你坚持做这件事，你就是在干傻事。