A former Mr. Universe who is one of the shortest winners of the body building contest has turned 100, saying on Sunday that happiness and a life without tensions are the key to his longevity.

Manohar Aich, who is 4 foot 11 inches (150 centimeters) tall, overcame many hurdles, including grinding poverty and a stint in prison, to achieve body building glory.

His children, grandchildren and great-grandchildren gathered on Sunday in the eastern city of Kolkata to celebrate his birthday the day before.

Hindu priests chanted prayers while a feast was laid out to honour Aich, winner of the 1952 Mr. Universe title.

Rippling his muscles and flashing a toothless grin, Aich says his ability to take his troubles lightly and remain happy during difficult times are the secrets to his long life. That, and a simple diet of milk, fruits and vegetables along with rice, lentils and fish have kept him healthy.

He does not smoke and has never touched alcohol, he said. "I never allow any sort of tension to grip me. I had to struggle to earn money since my young days, but whatever the situation, I remained happy," Aich said, sitting in a room decorated with posters and pictures of his many bodybuilding triumphs.

Aich, who was born in the small town of Comilla in Bengal, was a puny youngster. But he was attracted to exercising and building his muscles 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.

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

"It was in the jail that I began weight training seriously. This helped me prepare myself for the world championship," said Aich. "In jail I used to practice on my own, without any equipment, sometimes for 12 hours in a day," he recalled.

But the jail authorities were impressed with his perseverance and he was given a special diet to help build his stamina.

India's independence in 1947 led to Aich's release from jail. Dogged by poverty, Aich and his wife struggled to put their four children through school. There was little cash to indulge his passion for body building, but Aich took up odd jobs to earn a little on the side.

His 1950 win of a ‘Mr. Hercules’ contest spurred him to set his sights on the Mr. Universe tournament in London.

In 1951, Aich came second in the contest, and stayed on in London to prepare for another shot at the title. He returned to India after winning the title in 1952.

What followed were a host of awards, including top positions in Asian Body building Championships. Over the years, he also earned the more popular title of "Pocket Hercules" due to his 4 foot 11 inch-frame.

Six decades later, Aich helps his sons run a gym and fitness center and spends his days guiding juvenile hopefuls to reach the heights of body building that he did.

A minor stroke last year has robbed him of the ability to lift weights, but he keeps a watchful eye on young body builders training in his gym.

Although his two sons did not take up body building, Aich says his mentoring has earned him rewards. It has produced India's eight-time national champion, Satya Paul. Another protege, Premchand Dogra, snagged the Mr. Universe title in 1988.

Among his regrets, says Aich, is that he never had a chance to meet his more famous counterpart, a fellow Mr. Universe winner, Arnold Schwarzenegger. But Aich says he's seen many of Schwarzenegger's action films.

"I like the incredible stunts he does in the movies," Aich said.