Watford's Nathaniel Chalobah rejected a new contract at Chelsea after concluding he needed to leave to secure first-team football.The 22-year-old is also targeting a call-up to the England senior team, having been "excited" by Gareth Southgate's willingness to experiment with younger players.Like Bournemouth's Nathan Ake and Liverpool's Dominic Solanke, Chalobah finally chose to leave Chelsea earlier this summer in an attempt to progress his career.His fellow England Under-21 international Ruben Loftus-Cheek has similarly moved on loan to Crystal Palace, with Chelsea having recruited Tiemoue Bakayoko to further strengthen their options in central midfield.Chalobah is relishing the prospect of again feeling like he "belongs" at Watford, the club at which he built his reputation during a promising year on loan from August 2012.Less successful temporary moves to Nottingham Forest, Middlesbrough, Burnley, Reading and Napoli followed before he became a fringe player at Chelsea, but he is determined to take his chance back at Vicarage Road."I was offered a new contract but I decided to leave and hopefully get opportunities here," said the midfielder, part of the Under-21s team that reached the semi-finals of the European Championships."Leaving Chelsea was very emotional because I'd been there since I was a boy. I wanted to be part of (Watford) again and I wanted to feel like I belong somewhere."No disrespect to Chelsea but when I was here first time I did feel as if I was involved quite a bit and I did get opportunities."(My England prospects) were part of the reasons. It was just about trying to improve."(Marco Silva, Watford's new) manager was also something that was part of that. I'd heard some great things about him and I'd seen his work from last season (with Hull)."I felt like he would be the perfect guy to improve me and hopefully teach me some new things."Being (at Chelsea) last year, I saw how difficult it was to get in the team. You've got world-class players and all these players got to where they got to by playing games and putting their name out there."It was important for me to try to get that so I can say one day, 'Okay I've been there, got the experience I need and moved at the right time'."Since Southgate's appointment as England manager, he has given senior call-ups to several of those he worked with for the Under-21s, most recently Nathan Redmond and James Ward-Prowse.Chalobah played alongside each during Southgate's reign, and he said: "Anyone who has played in the ranks before, who is young, can get the opportunity."Gareth has made it clear with selections in Redmond and Ward-Prowse, if you are doing well at clubs you have an opportunity. For everyone who is in the England set-up it's exciting."They usually say 'The first loan is the worst loan' but for me (Watford) was my best loan. (Then) going out and dealing with not playing every week, living on your own, going to another country to speak another language: those are things I wouldn't change."(Tactical awareness) was something lacking in my game and I got taught about positioning (at Napoli), and it's something I'm working on, so it was the best way for me learning the game."