However, the 38-year-old former QPR, Tottenham and Newcastle striker, who was recently honoured in the Queens Birthday Honours, has been training with the Hornets to determine whether he can manage another season of Championship football.
"I'm realistic enough to know I can't do what I was doing at 26 or 27 but it's whether I can still offer enough to a team to make a difference," he told Sky Sports News.
"That's what I've got to weigh up in my mind.
"I said last year would probably be my last, so people have taken that on board that it was my last year, and I wasn't going to play again.
"I've been training at Watford, mainly to keep myself fit and see how my body feels and whether I can cope with the demands of another season in football.
"I love the game. I enjoy it and I am enjoying training, but I've got to really sit down over next few weeks and question Les Ferdinand and see if Les Ferdinand can do justice to himself and any team that decides they may want him."