The 78-year-old coach has taken charge of Bristol City until the end of the season following the dismissal of Gerhard Struber but the former England manager isn't interested in taking the job permanently.
Speaking at his first press conference in his new role, Roy - who hasn't coached since leaving Crystal Palace in 2024 after falling ill during training - said about why he took the job: "I think it was the fact that it was a short-term project, a short-term appointment.
"After the club made their decision to change, I think they were looking for someone who could step in and was prepared to do a job for seven games.
"Of course that appealed to me, because I have retired from the real maelstrom of working as a professional coach again, but I thought that I could manage five weeks - and I might even look forward to the five weeks, which has been the case so far.'
Asked directly if he could stay beyond the end of the season, he bluntly added: "No - I am too old.
"I hope to get some enjoyment from being here, to re-energise myself a little bit by being back on the grass and being back with players, something which has always been what I have wanted to do."
Bristol City are currently in 16th place in the Championship and face fellow relegation strugglers Charlton and Sheffield United over Easter weekend, and Roy is hoping they can "get results".
He said: "For me, it is going to be what happens on the pitch. I am here to coach the team and try and help the team to get results.
"I will only be satisfied if the people watching the team can see that is going on."