The actor filmed his final scenes as Aaron Livesy a month ago after four years in the role. Viewers will see the troubled character's exit episodes tonight (April 5).
Miller told This Morning today: "It's a weird feeling! I still say it hasn't sunk in yet. I still feel as if I need to be in [work] tomorrow at 7am.
"It was my decision. I had four years of such an amazing time, meeting amazing people - cast and crew. I love them all to bits and I was given so many good storylines. They trusted me so much on a big show at a young age.
"I just thought that I'd like to go and try other stuff before I get comfortable, because it's easy to get comfortable."
Aaron's final storyline has seen him desperately trying to protect best friend Adam Barton (Adam Thomas) by taking the blame for the fire he started at the garage.
Miller commented: "Tonight's two episodes is just basically Aaron moving on away from the village. But how does he? Does he go away to prison because he's due up in court, does he do a runner with Ed, or does he just run off into the middle of nowhere on his own? There's so many different ways he might go.
"Over the past four years, all you've seen is Aaron up in court, hurting people, upsetting people and getting away with it. Adam [has made] one drastic decision that could leave his life hanging in the balance, which might be prison.
"I think Aaron just wants to say, 'You're my best mate and it's about time that I stuck up for myself and for you. I'll take the rap for it, and you can start a new life as well as I can'. It's more about him growing up."
Emmerdale airs Aaron's exit tonight at 7pm and 8pm on ITV1.
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