Story highlights Lee Young-guk was bodyguard to the late North Korean leader Kim Jong Il for ten years

He remembers him as a man surrounded by terrified advisors

Lee was caught trying to escape in 1994 and sent to an infamous prison camp

He says he fears the current North Korean leader may be even worse than his father

Head butting stacked tiles, smashing a slab of granite on your chest with a mallet, breaking light bulbs with one finger. All vital qualifications if you want a job protecting the elite of North Korea.

Propaganda footage from North Korean TV shows a staggering array of physical feats, using taekwondo and other martial arts. Visually impressive -- although it's not certain how the skills would keep an armed assassin at bay.

Lee Young-guk was bodyguard to the late Kim Jong Il for 10 years until just before he took control of North Korea. He says he went through very similar training before he was considered fit to protect a leader.

"It's tough training," says Lee. "But why do it? It's to build up loyalty. A handgun won't win a war and taekwondo serves nothing but the spirit, but it creates loyalty."

Bodyguards 'brainwashed'

In an interview at CNN's Seoul bureau, Lee says his training also involved more traditional methods. Target practice, physical, tactical and weight training, swimming and using a boat. But that's only part of the preparation.

A large part of the training, he claims, is ideological brainwashing. Lee says he was trained to believe Kim Jong Il was a god -- and that the only reason he was born was to serve and protect the "Dear Leader."

But in the almost eleven years he stood by his side, he says he saw a man surrounded by fear.

JUST WATCHED North Korea: A new vacation hot spot? Replay More Videos ... MUST WATCH North Korea: A new vacation hot spot? 02:13

JUST WATCHED North Korea's dangerous new weapon Replay More Videos ... MUST WATCH North Korea's dangerous new weapon 01:45

JUST WATCHED Defectors describe horrors in N. Korea Replay More Videos ... MUST WATCH Defectors describe horrors in N. Korea 04:58

He recalls "two faces" to the man -- describing him as someone who could give out gold when he was happy, and death sentences when he was not.

"When Kim Jong Il would arrive in his vehicle, 60- to 70-year old advisors would run away and throw themselves onto the grass. They had dust on their clothes but they wanted to hide from him," says Lee.

"They are scared because even when he was happy he would be rude and could chop off their heads."

He remembers a senior official who once used Kim Jong Il's private elevator and ashtray. When Kim found out, he sent him to a concentration camp -- where the man died.

Kim Jong Un worst of all?

Lee knew the North Korean leader was cruel when he was serving him. But, he says, it was only after he escaped to South Korea, his new home, that he realized Kim was a true dictator -- as his father Kim Il Sung had been before him, and his son and current leader Kim Jong Un is now.

But he is worried that Kim Jong Un may be the worst of all. "Kim Jong Un ended up killing his uncle, who even Kim Jong Il could not kill," said Lee.

"As power was handed down to the third generation, it became crueler. Kim Jong Un has created loyalty, but it is fake and based on fear."

From experiencing the opulent palaces, food and women he says were in abundance in Kim Jong Il's entourage, Lee then saw the other extreme of life in North Korea.

After being caught trying to escape in 1994, he was sent to the infamously brutal Yodok political camp.

He eventually escaped, becoming one of an estimated 25,000 defectors who now call South Korea home. In his new life, he has worked as a duck farmer, written a book about his life in the North, and developed a career as a media pundit, speaking about his experiences on the other side of the border.

It was this desire to escape, and tell the world the story of what he had witnessed, that helped him survive the horrors of the camps, he says.