The 49-year-old filmmaker, who has directed movies like "The 40-Year-Old Virgin," "Knocked Up" and "Trainwreck," said he decided to work in TV after realising Dunham's talent, reported Entertainment Tonight.
"I didn't really plan to do TV. And then I met Lena and I just thought, Oh, this is such a special talent. I would do anything with her," Apatow said.
"The entire landscape of television changed and people would give you a season order and give you commitments. Now, what I like to do, which wasn't really built for network, is suddenly more in demand," he added.
"(I'm a) cog in the machine ... I can be very helpful at key moments, but, you know, the weight isn't on me. They do such a beautiful job that I couldn't have been less needed. I thought, I can only hurt this.