Henry's future beyond 2014 is up in the air with the 37-year-old's contract set to expire at the end of the season.
The Frenchman has been tight-lipped about his plans in 2015, while Red Bulls head of global soccer Gerard Houllier was quoted as saying Henry could retire, following the club's 1-0 friendly win over Arsenal last month.
And Donovan's announcement to call time on his career at the end of the MLS season - aged 32 - has only raised more doubt about Henry's own future, though the Arsenal icon insisted nothing has been decided.
"Some of my friends are telling me that I still look fit. I don't feel fit after games, though, but it is what it is," Henry told reporters on Friday.
"You have to respect anyone's decision. I said to you, as long as I can run, I will keep on playing.
"Sometimes it's not only down to your body, it's also what's happening up there in your head.
"We'll see. I still feel fresh, somehow, after a lot of games in my career. But I'm okay still so far."
