Resurrection of the Daleks

TEGAN: I'm not coming with you.

DOCTOR: I beg your pardon?

TEGAN: I'm tired of it.

DOCTOR: What's the matter?

TEGAN: A lot of good people have died today. I think I'm sick of it.

DOCTOR: You think I wanted it this way?

TEGAN: No. It's just that I don't think I can go on.

DOCTOR: You want to stay on Earth.

TEGAN: My Aunt Vanessa said, when I became an air stewardess, if you stop enjoying it, give it up.

DOCTOR: Tegan

TEGAN: It's stopped being fun, Doctor. Goodbye. Turlough.