Forty-three years in showbiz, over 180 films, national and international honours in his kitty and not to forget a huge fan following - Bollywood megastar Amitabh Bachchan has achieved a lot, but as an actor he never wants to be satisfied.

"I think every actor would wish there is some challenge that is left. I would consider to be creatively dead if I were to say that I am satisfied now," Big B told IANS in an interview in his trademark baritone.

"I think no actor should be ever satisfied because there is always something new to do, something fresh to get challenged by... I do hope there are filmmakers who will challenge me, who will create stories and characters that would excite me enough and provoke me to perhaps take up a job; so, as I said, I hope I never get satisfied," added the megastar who is called a "living legend" thanks to many milestones in his career.

From flops to stardom, from failure to scaling dizzying heights of success again, he has seen both good and bad times.

But he said he doesn't feel like looking back to his past, and added: "I don't spend much time looking back at what happened. I do remember it, but I don't see any purpose of wanting to look back. I should only look back at moments that were disparaging, look down upon, negative for me - moments where I could learn something. And if I have been able to use that learning in future, then I am happy about it."

A human being is on the right track if he or she learns from the bad phases of life, he said.

"I do believe that every human being will have ups and downs and I do believe that if we can learn from the periods when we were down, then we are on the right track.

"I would not want to change anything if I had to live another life. I would want the negatives to be there, I would want the downs to be there, because if everything is going to be good for you, then why are you here? You might as well be in heaven. There is some reason why we are here and this is what we all believe in," he said philosophically.

He wants to face "those obstacles because they taught me what I should be doing or how I should be conducting myself".

"If I haven't had all those obstacles, I would have never learnt all that. I feel blessed that I had downs in my life because they were actually lessons for me."

From "Zanjeer" to "Deewar", "Sholay" to "Shakti", he has playd larger-than-life characters on screen in his career, but says no role is big enough or too small.

"They are all tough roles. Every day is a test for me. It's an examination. No role is small enough, no role is big enough - they are all equal examinations...this is how I look at it.

"Whether it is a guest role, whether it's a passing role or a leading role - I always feel that there is a huge amount of concentration, work and the thinking process going into it. I treat each role with the same amount of equality," said Amitabh.

Recently he turned 70 and is wowing his fan as the host of "Kaun Banega Crorepati 6". He doesn't seem to have any plans to hang up his boots in the near future.