Russian photojournalist [Vladimir Yakovlev] started his Age of Happiness project in 2011, documenting people around the world who defy our expectations of ageing. Yakovlev has just published a book based on his project. Called How I Would Like To Be When I Am 70?, it features 30 people who refuse to age appropriately, including a 75-year-old surfer, a 103-year-old marathon runner and a 79-year-old porn star. "It started as a very personal project," says Yakovlev. "I was over fifty, I wanted to find out what can I expect in the future and most importantly to what extent I can affect whatever will be happening to me." Duan Tzinfu changed the way he lived when he spotted a group of people exercising in a Beijing park. "These were people much older than him who did the splits with ease. Duan couldn't even bend over without a big sigh," says Yakovlev, who photographed him in July 2011, at the age of 73. "After 50 years of working at a glass factory ... Duan could barely walk." But Duan joined the group, practising stretching and breathing exercises ... and now, aged 76, can perform moves that would challenge much younger people. Yakovlev has travelled to nine countries for his project, including France, Italy and India. Yakovlev describes the attitude that seems to link many of his subjects. "Pat Moorehead, a skydiver, celebrated his 80th birthday by making 80 skydives in a row, non-stop. He says: 'Happiness is just a choice, a life-style. I think that is true - about happiness ... and about staying young as well."