Oct.7 (GMM) Jean Alesi thinks Michael Schumacher had to retire because he is no longer as committed to winning.
"When you come back to racing such a machine, you have to make every sacrifice to be on the top," Frenchman Alesi told RMC Sport.
"If the car is not working as well, I think at a certain age this attitude has more of an importance."
Meanwhile, Jean Todt has offered a fascinating insight into Schumacher's decision to retire.
The great German announced his decision on Thursday, and Mercedes chiefs Norbert Haug and Ross Brawn admitted Schumacher only told them what he was going to say "five minutes" earlier.
But Todt, Schumacher's former Ferrari boss, a close friend and now the FIA president, said he knew all about it "a few days" earlier.
"I was told about Michael's decision a few days ago," he said. "We had the opportunity to speak, so I was prepared when he made it public and understood his reasons."
Todt, however, said he doesn't know what his friend is going to do next.
"I don't know, but he will be very busy, that's for sure," said the FIA president.