New Delhi, Dec 12 (IANS): Amitabh Bachchan, 72, is one of the busiest stars in the industry. Filmmaker Farhan Akhtar, 40, says he is truly inspired by the senor thespian's energy and hopes he's able to keep up the same enthusiasm at that age.

After directing him in "Lakshya", Farhan is now working with Amitabh as a co-star in "Wazir", which also features Aditi Rao Hydari and is directed by Bejoy Nambiar.

"It feels great to be working with someone whom I have admired throughout my life. It's difficult to say that if he does this (a certain thing), so I should also do that. That doesn't really happen.

"But what's most important is that you see someone working now for close to 50 years. It's very inspirational. I hope that I can have the same kind of enthusiasm when I would have worked for that many years," Farhan, who's finding the action sequences in "Wazir" quite thrilling, told IANS in an interview.

A multi-faceted talent who can act, sing, write, direct and produce, Farhan is the son of celebrated writer Javed Akhtar and child actress-turned-screenwriter Honey Irani, who are now separated.

He had once said that his mother was not particularly happy with his casual attitude towards life during his initial days in showbiz. But now, with projects like "Rock On!!", "Zindagi Na Milegi Dobara" and "Bhaag Milkha Bhaag" under his belt, he feels she's happier with his body of work.

Farhan, who is a father of two daughters with wife Adhuna, says when he looks back, he feels terrible about making his mother stress over his career.

"It was a very stressful time for her back then. I feel terrible in retrospect. At that point, I was too stubborn and rebellious to think about it. But now I do feel very bad that I stressed her to those levels. Hopefully, she is a lot happier now," said the director of films like "Dil Chahta Hai" and "Don: The Chase Begins Again".

The actor also makes a great working team with his sister Zoya, who is directing him next in "Dil Dhadakne Do".

Having worked under her direction in movies like "Luck By Chance" and "Zindagi Na Milegi Dobara", he says: "I have always enjoyed working with her. She has her own style of writing, has her own style of directing actors.

"There is also a certain comfort zone as we are very close to each other."