The 30-year-old has had a troubled time since coming back from an 18-month sabbatical in 2010. He was released by Saracens after just four games, then dropped by French side Toulouse three months into his contract following an alleged fight with a teammate on a night out.
Henson went on to sign an eight-month deal with Cardiff Blues but it too was terminated after an "incident" on a flight in which he allegedly "behaved inappropriately".
"Obviously I took time out of the game a couple of years ago. I was struggling physically and had a lot of stuff going on off the field," Henson told BBC London.
"I should be more mature. I don't think I am. I'm still a kid I think. But yeah, I am 30 now so I look after myself as best I can to try and prolong my career."
Henson added that he is now looking to end his professional career in the right manner, explaining: "How long I have left I have no idea [but] I'm still fighting and I still want to try and get back up there and finish on a more positive note."
Henson is expected to miss the first six weeks of Welsh's Aviva Premiership campaign after suffering an injury to his cheek bone in a pre-season friendly.