Gunners record goalscorer Henry insists he is not ready to play a full 90 minutes yet and warned he may not score in every game, despite netting less than 10 minutes into his second debut.
The 34-year-old Frenchman, on loan from New York Red Bulls until the end of next month, put his explosive impact down to taskmaster fitness coach Tony Colbert.
“I am nowhere near a 90-minute game but he did everything for me to be able to help,” said Henry, whose goal propelled Arsenal into the FA Cup fourth round, where they will meet Aston Villa.
“You are always going to get what you deserve if you work hard. That has always been my philosophy in the game: you have got to work hard.
“I would rather have the guy in my team who tries any day than the guy who doesn’t want to show up. That is my mentality.”
Henry’s winner against Leeds was his 227th goal for the Gunners on his 371st appearance, almost five years after he left north London for Barcelona.
Manager Arsene Wenger revealed his six-week loan includes an option to be extended to a maximum of eight weeks, keeping him at Arsenal until early March, but there is already a growing clamour among fans to prolong his stay.
Major League Soccer side New York Red Bulls, whose new season begins in March, may object, but either way Henry is eager to dampen expectations surrounding his already triumphant comeback.
“I know I scored but that is not going to happen every time I play,” Henry added. “I am going to try to bring what I can. Maybe another time it won’t be enough but I will always try my best.”
Wenger must now decide where Henry fits into a team currently built around his successor as the club’s main goal threat and captain, Robin van Persie.
The Holland star was rested on Monday but will return to the starting line-up for Sunday’s Premier League trip to Swansea, leaving Wenger with a conundrum over whether to play Henry in a wide role or leave on the bench.