Deeney has helped his team to be joint-top of the fledgling Premier League with three consecutive wins under boss Javi Gracia.
The Hornets now travel to Championship side Reading in the Carabao Cup on Wednesday and Deeney, who suffered an injury-hit last campaign feels like a new man since turning 30 in the summer.
“I have got a nutritionist and I am employing different people to look after myself, but that is because of the age I am at," said the striker.
“I am not naive and thinking I can do what I want and party like a rock star and still perform on the weekend. So I have started looking after myself.
“I have lost about a stone, but more in muscle mass than actual fat, and am just enjoying my football again.
“I got into a bit of a rut and it became a job for me. Once it becomes a job I don't really enjoy it, but I am enjoying it again now and that is showing. The good start is down to a good pre-season and having a bit of consistency with the manager."