Rippling his muscles and flashing a toothless grin a former Mr Universe known as the 'Pocket Hercules' celebrates his 100th birthday.

And what has been the key to long life for the super-fit centenarian who has battled poverty, a stint in prison and a minor stroke - not taking life too seriously.

The diminutive Manohar Aich, who is 4ft 11ins tall, overcame many hurdles to achieve his bodybuilding glory.

'Pocket Hercules': Former Mr Universe Manohar Aich flexes his muscles as he poses for a photograph on the eve of his 100th birthday in a gymnasium in Kolkata, India

Born in the small town of Comilla in Bengal, he was attracted to exercising and building hismuscles when as a schoolboy he saw a group of wrestlers in action.

After leaving school in 1942, he joined the Royal air force under India’s British colonial rulers and it was there that he began his relentless pursuit of body building.

Encouraged by a British officer named Reub Martin, who introduced him to weight training, Aich earned praise for his physique from his peers in the air force.

Heyday: The muscular Manohar Aich shortly after being crowned as Mr Universe back in 1952

Some years later, however, he was thrown into prison when he protested against colonial oppression.

He said: 'It was in that jail that I began weight training seriously. This helped me prepare myself for the world championship.

'In jail I used to practice on my own, without any equipment, sometimes for 12 hours in a day.'

Now and then: Indian body builder Manohar Aich looks at a print of one of his pictures hanging in a gym, in Kolkata 

Happy birthday: The pocket Hercules surrounded by family as he celebrates his landmark 100th birthday in India 

'I like the incredible stunts he does': Manohar Aich says that one of his biggest regrets is not having met fellow former muscle man Arnold Schwarzenegger