The Argentine forward played for a host of different clubs during the early part of his career, before making the move to Vicarage Road in 2012 on an initial loan deal.
He signed a long-term contract a few months later to make the switch permanent, and says that security over his future will stand him in good stead.
He told the Watford Observer: "I'm more relaxed. I've now finished the season and when I come back from Argentina, I know I'm coming back to England and Watford to my house and everything.
"I don't move. This is very important. I have another three years where I don't have to think 'what is happening with me?'."
Watford finished in mid-table last season and Forestieri is hoping they can push on next season under Giuseppe Sannino to compete for a play-off spot, although his main concern is staying fit.
The 24-year-old played just once in the final two months of the campaign after being hit by a hamstring injury and then a broken toe.
He said: "When I injured my toe it was a difficult moment because I came back on the pitch after my first injury and then got injured again. This moment, for me, is very sad because it meant no playing, no training. This is my life. If I don't play, then I'm sad."
Questioned about next season, he added: "I think it will be different because I hope with Sannino staying, everything will change.
"I hope maybe for the play-offs. I hope for no injuries first of all because one month or two months out of football is too much time for me."