Ekin Cheng Yee-kin said he was going through the toughest project of his career in frosty northern China. The 39-year-old actor is filming a mainland TV drama series, Huo Yuan-jia, in Beijing with friend Jordan Chan Siu-chun. Cheng (right) is famous for his mob leader role in The Young and Dangerous movie series back in the mid-1990s. 'It's extremely cold. Maybe it's because we're not from the north, but the cold is really unbearable for me,' he said. 'I said jokingly to Jordan Chan that this is the most painful working experience since we entered the industry. 'We've been to some really hot places to make movies. But this is our first time filming in such a cold environment. We eat hotpot everyday, to try and keep our bodies warm.'