The Arsenal legend took his first job in management at ASM last season and didn't last half a campaign.
Henry recalled to So Foot: "It's like everything: it's either you win or you learn. And I have always learned a lot more with difficulty than with ease. It's when you're tough that you know what you're made of.
"When everything is easy, you lead 8-0, everyone wants the ball. When you are down 1-0 or there is 0-0, it's not the same. In Monaco, I learned, as I learned this year and as I learn every day.
"Now, I'm talking to you, but next year I'll tell you something different. I can be sure of a tactic tonight and say to you two months from now, 'Um, actually, no, impossible'.
"As a coach, you can have ideas, but you also and above all have to adapt to the players you have, but also to the team you face. Afterwards, when you're Bayern or Manchester City, everyone adapts to you, obviously.
"I believe there is no exact science. Some will tell you the opposite, that they will stay with their 4-4-2, but I try to adapt and learn. This season, for example, we had imagined something with the staff, then we had to change depending on departures, injuries, the profile of the players ..."