He won his first race in 2010, beating all-comers at the Rome City Marathon to set a personal best of 2:08:39.
He began his professional career in 2005 and he set a personal best time of 2:11:26 to finish third in the Dubai Marathon.
[2] He competed in Asia for a second time that year and took fifth place at the Nagano Marathon, although he was leading the race throughout right until the 30 km mark.
Cold, wet weather severely affected the race, leaving him shivering as he crossed the line in 2:15:45, but his coach (former runner Haji Adillo) said he thought Gena could run around the 2:06 mark in good conditions.
[14] On November 17, 2013, Gena finished second at the Istanbul Marathon in a time of 2:13:19 hours behind French athlete Abraham Kiprotich.