The former Wales fly-half, who turned 39 in February, made his rugby league debut for West Wales Raiders on Sunday as they went down 58-4 to Widnes in the first round of the Betfred Challenge Cup at Stebonheath Park in Llanelli.
Henson told BBC Wales: “I learned a lot. It’s the first time I played the game. I watched it but there’s nothing quite like playing.
“It’s so relentless, it’s non-stop. I need to get fitter, basically. I think I did all right, I just couldn’t offer much because it was a very tiring game.”
The third-tier part-timers were outclassed by the seven-time cup winners but demonstrated plenty of spirit after being forced to play for most of the match with 12 men following the dismissal of centre Jamie Murphy for a dangerous tackle.
Henson added: “I think we started well. We were competing with them, finishing our sets, but losing a man killed the game for us.
“But it’s our first game of the season, emotions are running high and these things happen.
“We’ll take a lot out of it. It was like a training game in the end. The main thing for us is the league and we’ve got six weeks before that starts.”
Henson, who won 33 caps for Wales and represented the British and Irish Lions in a near 20-year career in union which ended when he was released by the Dragons in 2019, was given the job of kicking for the League 1 club.