The former Wales under-20 captain had limited opportunities in west Wales last season, starting only five games.
Myhill, 24, joined the Blues in May aiming to play more first team rugby.
"The last couple of years I had the feeling that whatever I did it wasn't going to change," he said.
"If I played well I still wasn't going to play, so I needed a change - a fresh start and just to kick on in rugby, really."
The presence of Wales internationals Ken Owens and Emyr Phillips at Parc y Scarlets meant Myhill faced a battle for first-team appearances - but he says he understands the reasons.
"There's two good players [Owens and Phillips] and a couple of young boys as well. They're all good players so I can see why the coaches came to the decisions they made," he added.
"There's no hard feelings or anything like that.
"I support the Scarlets anyway. I grew up supporting them. But now I'll just concentrate on the Blues and try to do well for them and win something."
Myhill was captain of Wales under-20 team that beat New Zealand in 2012.
He hopes the move to the Welsh capital will provide a new impetus to his senior career.
"I want to play more, try to improve and enjoy rugby again - because when you're not playing you don't really enjoy it," he added.
"But I'm really enjoying it with the Blues."
Myhill will again face tough competition for first-team selection, with current Wales squad player Kristian Dacey at the region and former Wales captain and British and Irish Lions hooker Matthew Rees having signed a one-year contract.
Myhill sees that front-row experience as a bonus.
"I learned most of my stuff off Smiler [Rees] at the Scarlets," said Myhill.
"I'm a young hooker so it's good to pick up stuff off him and the other internationals there, like [props] Gethin Jenkins and Rhys Gill."
Hooker Kirby Myhill says he has no hard feelings towards the Scarlets as he prepares for his first season with Cardiff Blues.